You’re solving for the volume of the cylinder. so the way you would do this is the area of the base of the cylinder (pi times radius squared) which in this case would be 3.14 x 10^2 which is 314. you would then multiply by h, the height, which here is 10. 314 x 10 is 3140.
I think it would be 8*9+8*16 which would be 72+128= 200
Keep in mind the the word "percent" translates to "for each 100." 25% can be read as "25 for each 100," which has the fractional representation

and the decimal representation 0.25. All of these representations are just different ways of writing the same value.
Note too that the fraction

can be reduced to

, so what the question is really asking is: 1/4 of what number is 9?
Well, if we know that 1/4 of the number is 9, we can easily find how large the whole number is by finding all 4/4 of it (the <em>whole</em> number)<em /><em />, or 4 x 9, which multiplies out to
36.
6 is the greatest common factor of 24,30,42