To do this, we're going to use the order of operations (PEMDAS):
P - Parentheses
E - Exponents
M - Multiplication
D - Division
A - Addition
S - Subtraction
First let's do parentheses, there isn't anythig in parentheses we need to simplify, so we can skip this step.
Next let's look for exponents. I see we have a
so let's replace that with
:

Now let's look for multiplcation. We know that things that are right next to eachother in parentheses represent multiplcation, so let's simply this more:



And now we're left with a simple problem we know how to solve.
Answer: 
Hope this helps!
Answer:
B
Step-by-step explanation:
6 ^ -7
So
1/2x+2=2/3x
convert to common fraction
1/2=3/6
2/3=4/6
3/6x+2=4/6x
subtract 3/6x from both sides
2=1/6x
multiply boh tisdes by 6
12=x
the tank can hold 12 gallon
Formula for volume of sphere V = 4/3 (Pi) r^3, where Pi ~ 3.14 and r is the radius = 7.
Therefore V = 4/3 * 3.14 * 7^3
= 4/3 * 3.14 * 343
= 4/3 * 1077.02
= 1,436.02667 cubic units