Hello! Remember you have to write complete questions in order to get good and exact answers. I'll help you to understand this problem, but I have to assume some things.
We know that the empty cup in the shape of a cylinder is being filled with water. Suppose the volume of this cylinder is:
[tex]V=450cm^3[/tex]
Suppose that the cup is filled at a constant rate of [tex]s=50cm^3/s[/tex], so in 7 seconds the cup is filled the following amount:
[tex]V'=50\times 7=350cm^3[/tex]
So this represents the following percentage:
[tex]\frac{V'}{V}\times100=\frac{350}{450}\times 100=77.78\%[/tex]
Finally, after 7 seconds the cup is 77.78% filled
