Step-by-step explanation:

Volume of a cylinder is formulated as: π·r²h
Surface area of a cylinder is formulated as: 2π·rh + 2π·r²
So, for a:
Volume = π·5²·12 = π·25·12 = 300π
Surface area = 2π·5·12 + 2π·5² = 120π + 50π = 170π
And it's essentially the same process for the other questions.
6u + 3u = 18
9u = 18
u = 18/9
u = 2
Answer:
2
Step-by-step explanation:
10-2=8.