Cathy lives in a state where speeders are fined $15 for each mile per hour over the speed limit. Cathy was given a ticket for $105 for speeding on a road where the speed limit is 60 miles per hour. How fast was Cathy driving?

Given :

Cathy lives in a state where speeders are fined $15 for each mile per hour over the speed limit.

Cathy was given a ticket for $105 for speeding on a road where the speed limit is 60 miles per hour.

To Find :

How fast was Cathy driving.

Solution :

Let, speed of Cathy is v miles per hour.

Number of miles per hour over the speed limit, n = v - 60 miles per hour.

It is given that speeders are fined $15 for each mile per hour over the speed limit.

So, total amount of fine for Cathy is :

105 = 15×( v - 60 )

v-60 = 7

v = 67 miles per hour

Therefore, Cathy was driving with speed of 67 miles per hour.