# How much pure antifreeze must be added to 12 L of a 40% solution to obtain a 60% solution?

Jun 29, 2017

#### Explanation:

First we need to determine the amount of antifreeze in the 12 L solution.

$0.4 = \frac{x}{12}$ $\Rightarrow x = 12 \cdot 0.4 = 4.8 L$

Then using the formula below:

$0.6$ = $\frac{4.8 + x}{12 + x}$

$0.6 \left(12 + x\right)$ = $\left(4.8 + x\right)$

$7.2 + 0.6 x$ = $4.8 + x$

$7.2 - 4.8$ = $x - 0.6 x$

$2.4 = 0.4 x$

$x = 6 L$