Two large storage tanks T and W contain water Tank has 900 gallons and W has 300 when will the two tanks contain the same amount of water if tank T starts losing water at the same time tank W starts to fill?

There's not enough info as the problem is stated. I think you left something out.

Doesn't a graph go with it?

The graph I saw for this exact problem has two lines and you're supposed to find where they will intersect.

Tank T has points at (0,900) and (3,750)

Tank W has points at (0,300) and (3,375)

Find the equations of the two lines using these data points, set them equal and solve.

I will give you a start. Tank T has line equation

Find the other and you're on your way.