Answer:
The step 4 is not what he should have done. But the wrong is step 5, because if he added -2x both sides, it would give the following equation:

and not 
Note that in step 4 he should have added 2x and not -2x to both sides, but we still have the equality. The problem is that step 5 is totally wrong.
I don't know what answer is expected to this question, but I would mark step 5, because this is mathematically wrong.
Solving the equation

Using distribution

Add
both sides


Add 12 both sides

Divide both sides by 5

Answer: it’s 20m long
Step-by-step explanation:
I can’t explain .—.
D) you just multiply the numerator and denominator by 6 to get an equivalent fraction
The slope-intercept form:

<em>add 27x to both sides</em>
<em>divide both sides by 9</em>

Step-by-step explanation:
$1.80 per pound
The amount she's supposed to buy it is
1.80 × 12.5 = $22.5
She paid $21.25 for the 12.5 pounds, that means she saved
$22.5 - $21.25 = $1.25
the amount she saved per pound is
1.25/12.5 = $0.1 per pound