I believe FH would be a line segment.
Hope this helps!
Answer: x=37.8, you can solve by writing a proportion
Let <span>simplify the equations

and

:
</span>
<span>1)
</span>
<span>and
</span>
<span>2)

.
</span>
<span>Equate the coefficients:
</span><span>
</span><span>

.</span>
Then

and mnp=24.
<span />
Lets say, for ease, that the vat can hold a total of 70 gallons (or whatever you would like to use.) Use whatever number you want, I just picked this because it gives us a lot of clean numbers.
Now, if the inlet can fill it in 7 hours, that means that it is adding 10 gallons per hour. (70 gal/7 hours = 10 gal/hr)
For the outlet, use the same process, and you find that it drains the vat at 7 gallons per hour.
So, if you subtract the outlet from the inlet, you get 10 - 7 = 3 gallons per hour added.
Now just divide the size of the vat by that number, and you find your answer.
70 gallons / 3 gallons per hour = 23 1/3 hours.