Evan washes two types of vehicles. It takes him 30 minutes to wash a car and 40 minutes to wash a truck. He charges $12 to wash a car and $15 to wash a truck. In 270 minutes, Evan made $105 washing cars and trucks. How many trucks did Evan wash?

1 answer

30 c + 40 t = 270 ... 3 c + 4 t = 27

12 c + 15 t = 105

solve the system

12 c + 16 t = 108