You drop a pencil out of window that is 20ft above the ground. use the formula v^2=64s, where v is speed and s is the distance fallen, to calculate the speed the pencil is traveling when it hits the ground.

First you substitute in the values so you have
V^2=(64)20
then you just simplify it
V^2=1280
V=the square root of 1280
V= about 35.7770876
or
V=the square root of 256 times the square root of 5
V=16 times the square root of 5

also V would typically be called velocity. it's very similar to speed but it is just easier to remember because it starts with a V

The answer is 15×7=105therefore, 105×5=525 miles