Answer:
Cathy was driving at a speed of 67 miles per hour.
Step-by-step explanation:
Fined $15 for each mile per hour over the speed limit. Cathy was given a ticket for $105.
We solve this using a rule of three.
1 mile - $15
x miles - $105
Applying cross multiplication:
15x = 105
x = 105/5 = 7.
Cathy was 7 miles above the speed limit.
How fast was Cathy driving?
7 miles above the speed limit of 60 miles per hour, so 60 + 7 = 67 miles per hour.
Cathy was driving at a speed of 67 miles per hour.