Question

Russ discovers at the end of the summer that his radiator antifreeze solution has dropped below the safe level. if the radiator contains 4 gallons of a 25% solution, how many gallons of pure antifreeze must he add to bring it up to a desired 50% solution?

Answer 1

Let's call x the pure antifreeze in gallons. This means 4 + x represents the new quantity of pure antifreeze.

According to the problem, 25% of the solution represents 4 gallons and 50% of the solution represents the new quantity of antifreeze.

Based on the given information, we can express the following.

$0.25(4)+x=0.50(4+x)$

Let's solve for x.

$\begin{gathered} 1+x=2+0.50x \\ x-0.50x=2-1 \\ 0.50x=1 \\ x=\frac{1}{0.50} \\ x=2 \end{gathered}$

Therefore, he needs to add 2 gallons of pure antifreeze.