#8
There are 6 sides. 15 and 1/4 cm for each side, call it 15.25
15.25(6) = 91.50 or 91 1/2 centimeters
#9

simplify to get

Now do


simplify to get your answer

feet
#10
5(2.5) = 12.5 square yards or 12 and 1/2 square yards
#11
2(0.25) = 0.5 square inches or 1/2 square inches
#12
3(7 and 1/10) which is the same 3(71/10) = 213/10 simplify to get 21 and 3/10 square centimeters