Question 162165
Pure acid is 100%
Convert % into decimal form 100/100
50%=50/100
80%=80/100

X=# of gallons of pure acid

1*x+7(.5)=(x+7)(.8)

Use the distributive property


x+3.5=.8x+5.6

Subtract .8x from both sides

.2x+3.5=5.6

Subtract 3.5 from both sides


.2x=2.1

Divide both sides by .2

x=10.5 gallons of pure acid

Let's double check our answer


10.5+3.5=(10.5+7)(.8)

14=14