From the statement of the problem, we know that:
• Rex paid $20 for a membership to the pool,
,
• and pays $3.00 each time he goes to the pool.
We define the variables:
• x = times that Rex goes to the pool,
,
• y = total cost.
The total cost is given by the sum:
• $3.00 x (what Rex pays every time he goes to the pool times the number of times),
,
• $20 the cost of the membership.
So we have:
Answer
Because none of the options is equal to the equation that we found, the correct answer is D. none of these.