Answer:
C. 17.5
Step-by-step explanation:
The current volume of the sandbox is 7Ă—5Ă—1 = 35 feetÂł
If six inches is added to the height, the new volume will be 7Ă—5Ă—1.5=52.5
To find the difference in how much the snadbox can hold, you can subtract. 52.5-35= 17.5