The gas tank of your car is 40% full. there are 8 gallons of gas in the tank. what is the capacity of the gas tank?

Percentage by which the gas tank of the car is full = 40%
Amount of gas in the gas tank = 8 gallons
Let us assume the capacity of the gas tank = x gallons
Then
40% * x = 8
(40/100) * x = 8
4x/10 = 8
4x = 8 * 10
4x = 80
x = 80/4
   = 20 gallons
So the total capacity of the gas tank of the car is 20 gallons. I hope the procedure is clear to you.

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