A druggist has two mixtures of a certain chemical and water, one containing 10% of the chemical and the other containing 40% of the chemical. How much of each mixture should he use to make 10 ounces that contain 25% of the chemical?

If x is the amount of 10% mixture used, then which expression represents the ounces of chemical contained in it?

Question

A druggist has two mixtures of a certain chemical and water, one containing 10% of the chemical and the other containing 40% of the chemical. How much of each mixture should he use to make 10 ounces that contain 25% of the chemical? 

If x is the amount of 10% mixture used, then which expression represents the ounces of chemical contained in it?

anonymous · Answer

0.1x 
x
10x

anonymous · Answer

10% of x is equal to 0.1x

Let say I used A ounces from the first mixture and B ounces from the second one.
Total of chemicals = 10*25% = A*10% + B*40%
10*0.25 = 2.5 = 0.1A+0.4B

Total of mixtures = 10 = A + B

You have two unknowns and two equations. Can you solve them?

anonymous · Answer

umm no lol sorry

anonymous · Answer

nvm i got it thanks

anonymous · Answer

When you have n unknows you need n equations two find them. Luckily we have 2 unknowns and 2 equations, we can solve them.

First find one of the A or B (doesn't matter which one you find)

anonymous · Answer

If you want I can solve them. It's very simple.

anonymous · Answer

to late lol thanks tho can you help with another problem?

anonymous · Answer

Solve for y:  y+10/y+3 = y+1/y-1