Math
posted by Derrick .
Robert and his dad want to build a sandbox for his sister's birthday.They wanted it to be 4 feet wide and have an area of 28 square feet.
What is the length of the sandbox?
7?
Robert's dad decided to make the sandbox bigger by extending the length and width of the sandbox by 24 inches. What is the area of the bigger sandbox?
When Robert and his dad finished building the sandbox,it was 2 feet tall.He wanted to fill up the sandbox with new sand.Each bag of sand cost $12 and covers 3 cubic feet. HOw much money will Robert's dad save by only fillinh the sandbox half way?
I don't know how to answer the 2nd and last question

2) 12in=1ft; 24in=2ft
4+2=8
7+2=9
8*9=72
Answer: 72ft^2
3)v=lwh
l=9
w=8
h=2
v=8*9*2
v=144ft^3
For # of sand bags if sandbox is completely filled:
144/3= 48
For $ used if buy it full:
48*12=576
$576
For # of sand bags if sand box is filled half way:
144/2=72
72=sand half filled
72/3=24
24 bags
For $ of sand half filled:
24*12=288
$288
Find the difference of the prices:
$576$288= $288
Answer: Robert's dad will save $288 by only filling the sandbox half way