Question

how many quarts of pure antifreeze must be added to 6 quarts of a 40% antifreeze solution to obtain a 60% antifreeze solution

Answer 1

3 quarts

Explanation:

First, find how many quarts of antifreeze is in the mixture.

0.4 x 6 = 2.4

Now, make it into a fraction by putting the antifreeze amount over the rest so:

2.4/6

Now add + a at the end of the numerator and bottom to make:

2.4 + a/ 6 + a.

Now, turn the percentage you want to strengthen or weaken the mixture into a percentage. So, 3/5.

Now, make it an expression by adding = 3/5 at the end of the equation.

2.4 + a/ 6 + a = 3/5

Now, use cross multiplication.

12 + 5a = 18 + 3a

Now, solve the equation.

12 + 5a = 18 + 3a

-3a. -3a

12 + 2a = 18

-12. -12

2a = 6

/2. /2

a = 3.

Therefore, the answer is 3 quarts.