Algrebra Question! Please help fast!! word problem!!

Question

A mixture of 7% disinfectant solution is to be made from 8% and 2% disinfectant solutions. How much of each solution should be used if 18 gallons of 7% solution are needed?

Answer 1

8 is much closer to 7 than 2 is. You'll need mostly 7% and relatively little 2% to get an 8% mixture

8x + 2(18-x) = 7(18)

8x + 36 -2x = 126

6x = 126-36 = 90

6x = 90

x = 90/6 = 15 gallons of 7%

18-x = 3 gallons of 2%

7 is within 1 of 8

7 is within 5 of 2

7 is 5 times closer

You need 5 times as much 7% as 2%

15 = five times 3