# If the price of gasoline increases by 25% and Ron intends to spend only 15% more on gasoline, by what % should he reduce the quantity of petrol that he buys?

Jul 26, 2016

8%

#### Explanation:

Suppose Ron buys quantity of gasoline today $= x$
Let today's price of gasoline be equal to $= y$
Ron spends on gasoline today $= x y$

The new price of gasoline is (increase by 25%)$= 1.25 \times y$
Ron wants to spend only 15% more,
$\therefore$he wants to spend$= 1.15 \times x y$
Quantity he buys at new rate$= \frac{1.15 \times x y}{1.25 \times y} = \frac{1.15 x}{1.25}$
Reduction in quantity of purchase$= x - \frac{1.15 x}{1.25} = \frac{0.10 x}{1.25}$
% Reduction in quantity of purchase of gasoline $= \frac{\frac{0.10 x}{1.25}}{x} \times 100$
=0.10/1.25 xx100=8%