Carcass wrote:
If the degree measures of the interior angles of a triangle are x, y, and z, where x = y/4 = 3z/5, what is the value of z?
(A) 20
(B) 30
(C) 45
(D) 60
(E) 100
Let's rewrite each angle in terms of x.
Given: x = y/4Multiply both sides of the equation by 4 to get:
4x = yAlso given: x = 3z/5Multiply both sides of the equation by 5 to get: 5x = 3z
Divide both sides of the equation by 3 to get:
5x/3 = zSince the three angles in a triangle must add to 180° we can write: x + y + z = 180
Substitute values to get:
x + 4x + 5x/3 = 180Eliminate the fraction by multiplying both sides of the equation by 3 to get: 3x + 12x + 5x = 540
Simplify to get: 20x = 540
Solve: x = 540/20 = 27
Now that we know x = 27, we can take the given equation: x = 3z/5
And substitute to get: 27 = 3z/5
Multiply both sides of the equation by 5 to get: 135 = 3z
Divide both sides of the equation by 3 to get:
45 = z Answer: C