if the sum and difference of two numbers are 20 and 8 respectively , then the difference of their square is :
"let the numbers be x and y . then , x + y = 20 and x - y = 8 x 2 - y 2 = ( x + y ) ( x - y ) = 20 * 8 = 160 . answer : c"
subtract(power(divide(add(20, 8), const_2), const_2), power(subtract(20, divide(add(20, 8), const_2)), const_2))