Question 7997
Well, you can always start by assigning variables to the quantities you are trying to find.

Let B = the number of blue cars and R = the number of red cars.

Now you have to translate the words of the problem into algebraic statements.

The fleet of red and blue cars is 24 cars. So, R + B = 24
There are 3 more (add 3 to)blue cars than twice (2 times) the number of red cars. Or, B + 3 = 2R

Now we have a system of two equations that we need to solve, Since the problem asks only for the number of red cars, we'll try and solve for R.

R + B = 24
B + 3 = 2R  Rewrite this as: B = 2R - 3 and substitute into the first equation.

R + (2R - 3) = 24 Simplify and solve for R.
3R - 3 = 24 Add 3 to both sides.
3R = 27 Divide both sides by 3.
R = 9 There are 9 red cars.

If you wanted to find out how many blue cars there are, take 24 - 9 = 15 blue cars.