. Here you have y − z and the other number, which you can call x. The average of x and y − z is 3y, so 3y =
x+y−z
2
. Multiplying both sides by 2 gives 6y = x + y − z. Subtracting y − z from both sides gives 5y + z = x. So the other number, x, is 5y + z, answer choice (E).