a) x and y are two numbers taken from the list below. 5 6 7 8 9 10 () What values of x and y will make 3x- 2y equal zero? (ii) Work out the greatest possible value of 3x– 2y. (ii) Work out the least possible value of 3x - 2y. b) Find the value of 5(a - 4b) when a = -7 and b = 1/4​