Answer:
x = 30
Step-by-step explanation:
Put in proportions
= 
Cross multiply and get 27x = 45 x 18
OR...
27x = 810.
THEN...
divide by 27 on both sides to get 30
x = 30
Answer:
(√138)/24
Step-by-step explanation:

Answer:
45 because you have to subtract 100-55 which would equal 45
Each side after the cut-out is (s-2c) where s is the original side length and c is the size of the cut so:
V=hlw, h=x and l and w are both (x-8)
V=x(x-8)(x-8)
V=x(x^2-16x+64)
V=x^3-16x^2+64x