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Re: If y = 4x + 10 and y = 7x – 5, what is the value of y? [#permalink]
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sandy wrote:
If \(y = 4x + 10\) and \(y = 7x - 5\), what is the value of y?

Show: :: OA
30


Here;

Let us multiply equation 1 with 7 = \((y = 4x + 10) * 7\) = \(7y = 28x + 70\)

multiply equation 2 with 4 = \((y = 7x - 5) * 4\) = \(4y = 28x - 20\)

Now subtracting both equation,
\(7y = 28x + 70\)
\(4y = 28x - 20\)
(-)_______________________

\(3y = 90\)
or \(y = 30\)
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Re: If y = 4x + 10 and y = 7x – 5, what is the value of y? [#permalink]
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Expert Reply
Explanation

Since each equation is already solved for y, set the right side of each equation equal to the other.

\(4x + 10 = 7x - 5\)

\(10 = 3x - 5\)

\(15 = 3x\)

\(5 = x\)

Substitute 5 for x in the first equation and solve for y.

\(y = 4(5) + 10\)

\(y = 30\)

x = 5 and y = 30. Be sure to answer for y, not x.
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If y = 4x + 10 and y = 7x – 5, what is the value of y? [#permalink]
Expert Reply
If \(y = 4x + 10\) and \(y = 7x - 5\), what is the value of y?

enter your value

Show: :: OA
30
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Re: If y = 4x + 10 and y = 7x – 5, what is the value of y? [#permalink]
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Carcass wrote:
If \(y = 4x + 10\) and \(y = 7x - 5\), what is the value of y?

enter your value

Show: :: OA
30


Since both equations are set equal to y, we can write: 4x + 10 = 7x - 5
Subtract 4x from both sides: 10 = 3x - 5
Add 5 to both sides: 15 = 3x
Solve: x = 5

Now that we know the value of x, we can take either equation (y = 4x + 10 or y = 7x - 5) and replace x with 5 to determine the value of y
So, take y = 4x + 10
Replace x with 5 to get: y = 4(5) + 10 = 20 + 10 = 30

Answer: y = 30

Cheers,
Brent
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Re: If y = 4x + 10 and y = 7x – 5, what is the value of y? [#permalink]
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As Y = 4X + 10 = 7X - 5
we find 15 = 3X
Or, X = 5.
so from the eqn we find Y = 30.
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Re: If y = 4x + 10 and y = 7x 5, what is the value of y? [#permalink]
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Given that y = 4x + 10 and y = 7x - 5 and we need to find the value of y

y = 4x + 10 = 7x - 5
=> 7x - 4x = 10 + 5 + 15
=> 3x = 15
=> x = \(\frac{15}{3}\) = 5

=> y = 4x + 10 = 4*5 + 10 = 20 + 10 = 30

So, Answer will be 30
Hope it helps!
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Re: If y = 4x + 10 and y = 7x - 5, what is the value of y? [#permalink]
1
Given that y = 4x + 10 and y = 7x - 5 and we need to find the value of y

y = 4x + 10 = 7x - 5
=> 7x - 4x = 10 + 5 + 15
=> 3x = 15
=> x = \(\frac{15}{3}\) = 5

=> y = 4x + 10 = 4*5 + 10 = 20 + 10 = 30

So, Answer will be 30
Hope it helps!
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Schools: XLRI Jamshedpur, India - Class of 2014
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Re: If y = 4x + 10 and y = 7x 5, what is the value of y? [#permalink]
1
Given that y = 4x + 10 and y = 7x - 5 and we need to find the value of y

y = 4x + 10 = 7x - 5
=> 7x - 4x = 10 + 5 + 15
=> 3x = 15
=> x = \(\frac{15}{3}\) = 5

=> y = 4x + 10 = 4*5 + 10 = 20 + 10 = 30

So, Answer will be 30
Hope it helps!
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Re: If y = 4x + 10 and y = 7x 5, what is the value of y? [#permalink]
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If \(y = 4x + 10\) and \(y = 7x - 5\), what is the value of y?

\(y=4x+10\) ---(1)

\(y=7x-5\) ---(2)

Substituting (1) in (2)

\(4x+10=7x-5\)

\(4x-7x=-5-10\)

\(-3x=-15\)

\(x=-15/-3\)

\(x=5\)

To find the value of \(y\), substitute the value of \(x\) in either of the equations.

\(y = 4(5) + 10\)

\(y = 20 + 10\)

\(y = 30\)

OR

\(y = 7(5)-5\)

\(y = 35-5\)

\(y=30\)

Either way, \(y = 30\).
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Re: If y = 4x + 10 and y = 7x - 5, what is the value of y? [#permalink]
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