A saves 18% of his income. If his income increases by 41% and he still saves the same amount. Find the percentage increase in his expenditure.

50%

Let the income of A originally be 100

Savings = 18

Expenditure = Income - Savings = 100 - 18 

                  = 82

Now, the Income increases by 41%

New Income = 141

Savings is the same, i.e. 18

Increased Expenditure =Increased Income - Savings = 141 - 18

                                 = 123

Percentage increase in expenditure = $\frac{123-82}{82}$ x 100 

                                                   = $\frac{41}{82}$ x 100 = 50%