a student gets 60 % in one subject , 70 % in the other . to get an overall of 70 % how much should get in third subject .
"let the 3 rd subject % = x 60 + 70 + x = 3 * 70 130 + x = 210 x = 210 - 130 = 80 answer : b"
subtract(multiply(70, const_3), add(60, 70))