the answer is 19 copies because the equation would be 81=4X+5 o by removing the five by subtracting on both sides you youd have an equation of 76=4x so by dividing by 4 on each side you would get 19=x so she can make 19 copies.
I believe this is true....lets say the plane takes off and goes up 500 ft.....it circles, but then it has to come back down...land...so it comes down 500 ft... 500 - 500 = 0
