man spends 75% of his income. His income increases by 20% and his

expenditure also increases by 10%. Find the percentage increase in his
savings.

Let's assume the man's income is $100.

Initially, he spends 75% of his income, which is 0.75 * 100 = $75.

His expenditure increases by 10%, so his new expenditure is 1.10 * $75 = $82.50.

His income increases by 20%, so his new income is 1.20 * $100 = $120.

Therefore, his new savings would be $120 - $82.50 = $37.50.

Initially, his savings were $100 - $75 = $25.

So, the percentage increase in his savings is ((37.50 - 25) / 25) * 100% = 50%.

Therefore, the man's savings increase by 50%.