Laura is hosting a carwash. She will charge $5 for a car, $6 for a truck, and $7 for an SUV. They raised $100 in total. If they washed 5 SUVs and 5 trucks, how many cars did they wash?
Thoughts? Step-by-step reasoning:
They earned $30 from trucks because 5 x 6 = 30. They earned $35 from SUVs because 5 x 7 = 35. They earned $35 from cars because 100 - 35 - 30 = 35. They washed 7 cars because 35 / 5 = 7.
Thus, the answer is 7.