Answer: 140
Explanation:
First you find 10% of 400.0 so you move the decimal point once to the left to get 40. Then you do 40 x 3 which is 120 this is 30%. To work out 5% you half 10% was 40. Half of 40 is 20. So 30%+5% is 35%. 30% is 120 and 5% is 20. 120+20 is 140