a student gets 50 % in one subject , 60 % in the other . to get an overall of 60 % how much should get in third subject .
"let the 3 rd subject % = x 50 + 60 + x = 3 * 60 110 + x = 180 x = 180 - 110 = 70 answer : b"
subtract(multiply(60, const_3), add(50, 60))