a chemist mixes a 21% acid solution with a 15% acid solution. How many millimeters of each solution should the chemist use to make 84 millimeters of a 17% acid solution

Answer 1

21X + 15(84-X) = 17(84)

21X -15X = 17(84)-15(84) = 2(84) = 168

6X = 168

X = 168/6 = 28 liters of 21% solution

84-X = 84-28 = 56 liters of 15% solution

21(28)+56(15) = 17(84)

588+ 840 = 1428

1428=1428

15 is within 2 of 17

21 is within 4 of 17

4 = twice 2

you need twice as much of 15

2(28) = 56