need help with this

[mellow niche]

I believe that is correct (though I couldn't say if it's the intended solution)

you can solve it with calculus as well

[olive steppe]

invariance.

[mellow niche]

You can get the answer by differentiating the equation
[V = \frac{16}{75} x^3]
with respect to time and evaluating (\frac{dx}{dt}) at (x = 8).

[olive steppe]

invariance.

[lean lichen]

i got the answer already but thanks a lot