Answer:
Andrew has 9 cars
Step-by-step explanation:
Let's start by defining what our unknowns are and how to name them:
For the number of cars Andrew has: let's use the letter A
For the number of cars Luke has: let's use the letter L
Not write the first sentence in mathematical terms:
"Luke has 4 more than triples the number of cars that Andrew has."
L = 3 * A + 4
The second phrase results on a very simple equation since it just states the number of cars that Luke has:
L = 31
Now we can combine these two equations by replacing the variable "L" in the first equation with the second equation and then solve for A:
L = 3 * A + 4
31 = 3 * A +4
31 - 4 = 3 * A
27 = 3 * A
A = 27/3
A = 9
Therefore, Andrew has 9 cars.