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?
They earned $30 from trucks because 5 x 6 = <<5*6=30>>30
They earned $35 from SUVs because 5 x 7 = <<5*7=35>>35
They earned $35 from cars because 100 - 35 - 30 = <<100-35-30=35>>35
They washed 7 cars because 35 / 5 = <<35/5=7>>7
#### 7