Problem Solving

If 1,500 is increased by 20% and then reduced by \(y\%,\) yielding 1,080, what is \(y ?\)

(A) 20
(B) 30
(C) 40
(D) 50
(E) 60

[spoiler]OA=C[/spoiler]

Source: Manhattan GMAT

When 1500 is increased by 20% it becomes \(\frac{120}{100}\ \cdot\ 1500\ =\ 1800\)

Now when 1800 is decreased by y% it becomes 1080.

So $$\frac{\left(100\ -\ y\right)}{100}\ \cdot\ 1800\ =\ 1080$$
\(\left(100\ -\ y\right)\ \cdot\ 18\ =\ 1080\) $$\left(100\ -\ y\right)=\ \frac{1080}{18}\ =\ 60$$ $$y\ =\ 40$$ C