SOLUTION: David's gas tank is 1/6 full. After he buys 7 gallons of gas, it is 1/2 full. How many gallons can David's tank hold?

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Question 629684: David's gas tank is 1/6 full. After he buys 7 gallons of gas, it is 1/2 full. How many gallons can David's tank hold?
Found 3 solutions by ewatrrr, richwmiller, 55305:
Answer by ewatrrr(24785)   (Show Source):
You can put this solution on YOUR website!

Hi,
David's gas tank is 1/6 full.
After he buys 7 gallons of gas, it is 1/2 full. 2/6 = 1/3 of Tank is 7 gal
Gas Tank is a 21 gal tank

Answer by richwmiller(17219)   (Show Source):
You can put this solution on YOUR website!
x/6+7=x/2
multiply by 12
2x+84=6x
84=4x
21=x
check
21/6+7=21/2
10.5/3=10.5-7
10.5=3.5*3
ok

Answer by 55305(86)   (Show Source):
You can put this solution on YOUR website!
Lets start with what fraction of the tank he filled with gas. So 1/2-1/6= 3/6-1/6= 2/6= 1/3 So he bought 1/3 as many gallons as the tank holds, which is 7 gallons. So that means his tank must hold 21 gallons.