The tank at a gas station contained 400 gallons of gas. a tanker truck that contained 8,100 gallons of gas filled the station's tank. after that the tanker truck had 4 times as much gas as the station's tank. how much did the tanker truck put into the station's tank?

1300

Step-by-step explanation:

Let the amount put in the station's tank = x

4(400 + x) = 8100 - x                           Remove the brackets

1600 + 4x = 8100 - x                            Subtract 1600 from both sides

1600 - 1600 + 4x = 8100 - 1600 - x     Do the subtraction

4x = 6500 - x                                        Add x to both sides

4x + x = 6500 - x + x        

5x = 6500                                            Divide by 5

5x/5 = 6500/5                                      

x = 1300

1300 gallons were added to the station's tank.

Step-by-step explanation:

Givens

In this problem, the unknown variable represents the amount of gas the truck filled to the gas station. So,

expresses the tank of the gas station filled

represents the amount of gas is taken out of the truck, which is the same amount that it's being filled to the station.

expresses the comparison between the gas station and the truck, the tank of the truck (after filling) is four times the tanks of the gas station.

Now, we solve for

Therefore, the tanker truck put 1300 gallons of gas into the station's tank.