The capacity of an automobile cooling system is 16 quarts. it is half full of a 15% antifreeze solution. the owner is adding
2 gallons of a 90% solution (remember, 1 gallon - 4 quarts), when he is finished, what will the solution's percentage
value be?

52.5%

Step-by-step explanation:

16 quarts is the capacity, in gallons that is:

16/4 = 4 gallons

It already has 2 gallons (half of 4 = 2) of 15% antifreeze. There are:

15% of 2 = 0.15 * 2 = 0.3 gallons of antifreeze

owner adds 2 gallons of 90% antifreeze, so antifreeze added is:

90% of 2 = 0.9 * 2 = 1.8 gallons of antifreeze

Now, in total there is 0.3 + 1.8 = 2.1 gallons of antifreeze

and

total amount of solution is:

2 gallons from before

2 gallons added by owner

= 4 gallons in total

To find percentage of antifreeze, we divide amount of antifreeze (2.1) by total amount of solution now (4), thus we have:

2.1/4 = 0.525

Multiplying by 100, we get:

0.525 * 100 = 52.5%