$30 because you are taking away 20% of $30 and then adding back that 20%.
Answer:

Step-by-step explanation:
Given

Required
Find the equivalent
We start by changing the / to *


Factorize 10a - 5

Expand 4a² - 1


Express (2a)² - 1² as a difference of two squares
Difference of two squares is such that: 
The expression becomes

Combine both fractions to form a single fraction

Divide the numerator and denominator by 2a - 1

Simplify the numerator


Hence,
= 
The answer to your question is X = -8
Answer:
The correct answer is 1/2×8×3.
hmmm, between the three options I would go with the second one since the number of 1-foot cubes equals exactly the volume of the fish tank.
But to truly calculate the volume
5 x 3 = 15
15 x 3 = 45
45 is the volume of the fish tank