if tim had lunch at $ 50.50 and he gave 15 % tip , how much did he spend ?
"the tip is 20 % of what he paid for lunch . hence tip = 15 % of 50.50 = ( 15 / 100 ) * 50.50 = $ 7.575 total spent 50.50 + 7.575 = $ 58 correct answer a"
add(50.50, divide(multiply(50.50, 15), const_100))