Respuesta :

let x is car
     8x truck

x + 8x = 18
9x = 18
divide both sides by 9
9x/9 = 18/9
simplify
x = 2

So car = 2
Truck = 8x = 8*2 = 16

Answer is 2 cars.

Double check : 2 + 16 = 18 vehicles total