Algebra-1

Set the amount of fuel needed in the first stage is x, and the amount of fuel needed in the second stage is y. making a system of equation like:

Since the total fuel available is 6000 liters, thus:

x + y=6000

Since the first stage requires 3 times the amount of fuel as the second stage, thus:

x = 3y

Substitute x = 3y into the first equation:

3y + y = 6000

4y = 6000

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