Answer:
Step-by-step explanation:
This is related rates in calculus, as far as I can tell from the info you've provided. It's nice to see students are still trying to conquer its vagueness!
Start with the formula for volume of a cylinder:
and then find its derivative with respect to time:

From that formula it looks like we need a value for dV/dt, r, dh/dt, and h; dr/dt is our unknown. We have that
dV/dt = -171
dh/dt = 6
h = 6 and
V = 1254
We need a value for r. We can find it using the last 2 values listed above in the volume formula:
and
and
and
r = 8.156394
NOW we have everything we need to fill in the derivative for the volume:
which simplifies to
and
so
ft/sec