30+(20x)=y
30 is the money you had from the start of the garage sale.
20 is what you are getting per hour
y equals the total money you are earning at the end of the garage sale
X=Marks sister's age
x+11= Marks age
x+11 +8 = 2x+8
x+19=2x +8
x+19-x=2x-x +8
19-8=x+8-8
11=x Marks sisters age in 8 years
11-8= 3 Marks sisters age now
x+11=22 Marks age in 8 years
22-8= 14 Marks age now
Length of each side of cube is =

SO the volume of cube =

=

=

=

SO the volume of cube is