if the sum and difference of two numbers are 20 and 10 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 * 10 = 200 . answer : d"
subtract(power(divide(add(20, 10), const_2), const_2), power(subtract(20, divide(add(20, 10), const_2)), const_2))