Problem: if the average ( arithmetic mean ) of x and y is 80 , and z – x = 100 , what is the average of y and z ?
Rationale: "x + y / 2 = 80 = > x + y = 160 x = z - 100 . . . sub this value z - 100 + y = 160 = > z + y = 260 = > z + y / 2 = 130 answer : e"
annotated_formula: subtract(multiply(100, const_2), multiply(80, const_2))