Matthew currently has enough money to buy 45 toy cars. If the cost of each car was 10 cents less, Matthew could buy 5 more cars. How much money does Matthew have to spend on toy cars?

The answer is $45

Let's make the system of equations.

x - the cost of the car

y - the amount Matthew has

Matthew currently has enough money to buy 45 toy cars:

y = 45x

If the cost of each car was 10 cents less, Matthew could buy 5 more cars:

y = (x - 10) * (45 + 5)

45x = (x - 0.10) * 50

45x = 50x - 5

5 = 50x - 45x

5 = 5x

x = 5 / 5

x = 1

y = 45x = 45 * 1 = $45