Jose wants to make a 8.5 ml of a 78% saline solution by mixing together a 70% saline solution and a 80% saline solution. How much of each solution must he use?

Question

 I can't figure out the formula

Answer 1

x represents amount of 70%

8.5 - x represents amount of 80%

 

0.70x + 0.80(8.5 - x) = 0.78(8.5)

 

Can you solve for x and answer?