Let expense = 500 , savings = 300 & income = 800 So new expense = 500+ 18% of 500 = 500 + 90 = 590 & new income = 800 + 15% of 800 = 800 +120 = 920 So new savings = 920 – 590 = 330 ∴ Required % increase in savings= (330 – 300 ) /300× 100 = 30 /300×100% = 10%