The price (per litre) of petrol increases by 60%. By what percent should its consumption be reduced such that the expenditure on it increases by 44% only?

Correct option is C

Given:

The price of petrol increases by 60%.
The expenditure on petrol increases by 44%.
Formula Used:
Expenditure = Price × Consumption
Solution:
Let the original price of petrol be  P and the original consumption be  C.
Original expenditure =$$P \times C .$$​
After the price increase:
New price = P + 0.60P = 1.60P 
Let the new consumption be C' .
New expenditure =$$1.60P \times C'.$$​
New expenditure = Original expenditure + 44% of original expenditure
​$$1.60P \times C' = 1.44 \times (P \times C) .$$​
​$$1.60P \times C' = 1.44P \times C$$​
C' =$$\frac{1.44P \times C}{1.60P}$$​
C' =$$0.90 \times C$$​ 
Reduction = C - C' = C - 0.90C = 0.10C .
Percentage reduction =$$\frac{0.10C}{C} \times 100\% = 10\%$$

Alternate Method:

The price of petrol increases by 60%.

Then, 100 + 60 =160

The expenditure on petrol increases by 44%.

100 + 44 = 144

So, Reduction= 160 - 144 =16

Percentage reduction =$$\frac{16}{160}\times 100 =$$10%