if a gas tank currently contains 15 L of gas and is three eights full how many additional liters of gas are needed to fill up the tank ?

Answer 1

The first thing to consider when looking at this problem is "in simple words, what is the question asking?"

"How many additional liters of gas are needed to fill up the tank" tells us that we are looking for how much gas we need to fill the gas tank. The unit will be in liters.

Next we look at what we know.

We know that the gas tank is 3/8 full, and that it has 15 liters of gas in it.

Now we can set this up in terms of an equation:

(3/8)x = 15

3/8 of the total tank is 15 liters, where x = the total volume of the tank.

We are looking for how much more we need, in addition to the 15 liters we have, to fill the tank.

That equation would look like:

15 + y = x

Where y = the volume we need to fill the tank.

Next we solve for x:

(3/8)x = 15

3x = 15(8)

3x = 120

x = 120/3

x = 40

But we're not done!

This gives us the total volume of the tank. But we already have 15 liters of gas in the tank, and remember, we need to know how much more we need.

So we solve for y, substituting 40 in for x.

15 + y = 40

y = 40 - 15

y = 25

We need 25 liters of gas to fill the tank.