A certain parking lot has red, white, and blue cars. The number of red cars is 3 more than the number of white cars, and the number of blue cars is 2 times the number of red cars. What could be the total number of cars in the lot?

Question

19, 20, 21, or 22?

Answer 1

r=w+3
b = 2r
so the total number of cars is w + w+3 + 2(w+3) = 4w+9
21 = 4*3 + 9