Question

A man spends 75% of his income, when his income is increased by 20%, he increases his expenditure by 10%. by how much per cent are his savings increased

Answer 1

Let us assume his income is Rs . 100.
Now A/Q his expenditure is 75 %  i.e.  Rs . 75

So his savings = S1 = 100-75 = RS . 25

Later his income increases by 20%  → 100 + 100 x  20/100 =  Rs. 120
and his expenditure increases by 10% → 75 + 75 x 10 /100  = Rs. 82.5

So his savings = S2 = 120 - 82.5 = Rs . 37.5
Increment in savings = S2-S1 = 37.5 - 25 = Rs. 12.5

percentage increase = 12.5 / 25 x 100 = 50 %

Hope this assists.