For every 2 red cars there are 3 blue cars in the dealership. If there are 535 cars, how many red cars are there? How many blue cars are there?
r = red cars
b = blue cars
The ratio of the number of red cars to the number of blue cars is 2 to 3
r / b = 2 / 3
Cross multiply
3 r = 2 b
Divide both sides by 3
r = 2 / 3 b
The sum of the number of red cars and the number of bue cars is 535.
r + b = 535
Replace r with 2 / 3 b in this equation.
2 / 3 b + b = 535
2 / 3 b + 3 / 3 b = 535
5 / 3 b = 535
Multiply both sides by 3
5 b = 1605
Divide both sides by 5
b = 321
r = 2 / 3 b = 2 ∙ 321 / 3 = 642 / 3 = 214
There are 321 blue cars and 214 red cars.