Algebra help please

Question

a pharmacy wants to mix a 36 saline with a 12% saline solution to get 169 mL of a 33% saline solution. how much of each should be used? Rounding to the nearest mL.

Answer 1

we want a total of 169 ml.

If we use x ml of 36%

then we add (169-x)ml of 12%

 

Look at the saline concentrations:

x ml at 36% has 0.36 ml saline.

Add to that (0.12)(169-x) ml saline.

To sum to 0.33(169) ml saline.

 

0.36x + 0.12(169-x) = 0.33(169)

To simplify multiply both sides by 100:

36x + 12(169-x) = 33(169)

 

Solve for x to find ml of 36% saline,

Then use 169-x to find ml of 12% saline.