C=2pir
20pi=2pir
20pi/2pi=2pir/2pi
R=10
Height=10/2=5
Two circles surface areas is
2*pir^2
2pi10^2
2*100pi
200pi
The cylindrical part is
2pirh
2pi*10*5
100pi
Add 100pi+200pi=300pi
So,
First, we find the prime factored form (P.F.F.) of 65 and 91.
P.F.F. of 65: 5 * 13
P.F.F. of 91: 7 * 13
Find the common numbers
13
13 = G.C.F.
Note: This method works for finding any G.C.F. (find common primes)
If you're doing probabilities, there is a 1:6 chance on both (im guessing dont trust me i did probabilities a long time ago)
S= Sydney
devaughn= s-13
so s+s-13=75
2s-13=75
now I think you can solve the rest.