How many liters of antifreeze do you need?

Question

A radiator holds 7 liters. Suppose you have a bottle of pure antifreeze and a bottle of 10% antifreeze mixture. How much of each must you need to make enough of a 74.28% mixture to fill the radiator?

How liters of pure antifreeze?


How many liters of 10% antifreeze?

Answer 1

x represents the amount of pure antifreeze

7 - x represents the amount of 10%

 

x + 0.1(7 - x) = 74.28(7)

100x + 10(7 - x) = 74.28(7)    multiply both sides by 100 to eliminate decimals

100x + 79 - 70x = 519.96

 

 

Can you solve for x?