a student got 70 % in one subject , 80 % in other . to get overall 75 % how much he should get in third subject .
already average of two subjects is ( 70 + 80 ) / 2 = 75 % to maintain the percentage at 75 % , he shouls get 75 % marks in third subject answer : b
divide(add(add(70, 80), 75), const_3)