Question 186873
A mixture contains 40 ounces of glycol and water and 10% glycol.
If the mixture is to be strengthened to 25%, how much glycol is to be added?
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First step
let x = amt of glycol required
;
Write a percent glycol equation. (Pure glycol = 1.0x)
.10(40) + x = .25(x + 40)
:
4 + x = .25x + 10
:
x - .25x = 10 - 4
:
.75x = 6
x = {{{6/.75}}}
x = 8 oz of glycol required
;
:
Check solution in the equation (48 oz resulting total)
.1(40) + 8 = .25(48)
4 + 8 = 12 
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How about this? Did it make sense to you?