We know that the skid marks (d)= 150 feet.

S= speed in miles per hour (what we have to figure out)

0.75*150=112.5 (left side is now figured out)

Now we have to figure out s^2/30.25

Let's multiply both sides by 30.25

s^2*30.25/30.25=112.5*30.25

s^2=3402.125

Square root of 3402.125=58.3277378

Rounded: 58

So our answer is about 58 miles per hour.