One solution was 10 fluorine and the other was 30 fluorine H

One solution was 10% fluorine, and the other was 30% fluorine. How much of each should be used to get 200 ml of a solution that is 17% fluorine? Sandy ran out at 8 mph and rode back to Ski Island in a jitney at 24 mph. If the total trip took 8 hours, how far did she run and how far did she ride?

Solution

3. Let x ml of 10% fluorine is mixed with y ml of 30% fluorine is mixed

x + y = 200 ----(1)

0.1x + 0.3y = 0.17*200

0.1x + 0.3y = 34 ----(2)

Multiply equation 1 by 0.1

0.1x + 0.1y = 20

0.1x + 0.3y = 34

---------------- - 0.2y = -14

y =70 ml ; x = 130 ml