Answer:
You earn 20$ for washing 4 cars.
You washed 9 cars to get 45$.
Hope this helps!
Explanation:
If you earned 35$ for washing 7 cars, one car is 5$ ( 35 ÷ 7 ).
If one car is 5$, 4 cars is 20$ ( 5 * 4 ).
Because one car is 5$, the 45$ is 9 cars ( 45 ÷ 5 ) or ( 9 * 5 ).