We are given : $168 raised for washing 24 cars and $280 raised for washing 40 cars.
We know the rate formula.
Rate = Total amount ÷ Total numbers.
Let us find value of each rate for the given problem.
Rate 1: Total amount ÷ Total numbers = $168 ÷ 24 = $7.
Rate 2: Total amount ÷ Total numbers = $280 ÷ 40 = $7.
We can clearly see that Rate 1 is equal to Rate 2, that is $7.
So, we can say rates are equivalent.