Question 617776
the equation(s) are set up based on the "active" ingredient -- in this case, the acid


the final product is 12L of 36% acid
___ to get that, you mix some amount of 18% acid; with -- 12L minus that amount -- of 45% acid


(x)(18%) + (12 - x)(45%) = (12)(36%) ___ multiplying by 100 to clear the percents is usually a good idea


18x + (12 * 45) - 45x = (12 * 36)


(12 * 45) - (12 * 36) = 45x - 18x


12 * 9 = 27x ___ 4 = x