With this problem solving question it would be easier to plug in numbers.
Let's say that:
K=5
X=1
6=6
Y=10
So the liquid leaks out at a rate of 5l per hour, every litre cost 6$ and every hour costs 30$.
If Y= 10 the cost of the liquid per hour (30$) multiplied by Y(10) equals 300.
Our target is 300.
Plug in the numbers in the answer choices and the answer that yelds 300 will be the right one.
A \(\frac {ky}{6x}\) = 5(10)/6= 8.333333
B \(\frac {6x}{ky}\) = 6/5(10)= 0.12
C \(\frac {6k}{xy}\) = 6(5)/10 = 3
D \(\frac {6ky}{x}\) = 6(5)(10)/1 = 300
CORRECT (we could stop at D but if you have time go ahead)
E \(\frac {6xy}{k}\) = 60/5 = 12
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