The fastest speed of the William is 7.5 miles per hour. Then the correct option is D.
It is a system of an equation in which the highest power of the variable is always 1. A one-dimension figure that has no width. It is a combination of infinite points side by side.
William’s typical running speed is 6 mi/h.
The difference between his fastest speed and his typical speed is 1. 5 mi/h.
The equation f - 1.5 = 6 can be used to represent this problem, where f is William’s fastest speed. Then we have
f - 1.5 = 6
f = 6 + 1.5
f = 7.5 mi/h
The fastest speed of the William is 7.5 miles per hour. Then the correct option is D.
More about the Linear system link is given below.
https://brainly.com/question/20379472