a student gets 60 % in one subject , 80 % in the other . to get an overall of 75 % how much should get in third subject .
let the 3 rd subject % = x 60 + 80 + x = 3 * 75 140 + x = 225 x = 225 - 140 = 85 answer : c
subtract(multiply(75, const_3), add(60, 80))