Answer:
(A) the subtraction property of equality
Step-by-step explanation:
Given
The steps in the question
Require
Justify step 2 to 3
Write out step 2:

Apply subtraction property by subtracting 2x from both sides


Notice that the above equation is represented in step 3.
<em>Hence, option A answers the question.</em>
Any answer less than one would work, soothe answers are A and D
Like 9 and 9? 9 is a multiple of 3 and 9 time 9 is 81
Answer:
D. The rate of change must be 20 pounds per minute.
Step-by-step explanation:
At time 0, the amount of sand is 200 lb. Time zero is when it starts, so it is also called the initial time. The initial value is 200 lb, so choices A and B are wrong.
Now look at the difference from time 0 minutes to time 1 minute. The amount of sand went from 200 lb to 220 lb. The amount of sand placed in 1 minute is 20 lb, so the rate of change is 20 lb per minute. That makes choice C wrong and choice D correct.
Answer: D. The rate of change must be 20 pounds per minute.