if the average ( arithmetic mean ) of x and y is 40 , and z – x = 60 , what is the average of y and z ?
"x + y / 2 = 40 = > x + y = 80 x = z - 60 . . . sub this value z - 60 + y = 80 = > z + y = 140 = > z + y / 2 = 70 . answer : d"
subtract(multiply(60, const_2), multiply(40, const_2))