Answer
The inequality equation is
(9 + x) ≤ 15
The solution is
x ≤ 6 pounds
The number of pounds that the parents can add to the shipment without having to pay additional shipping costs is less than or equal to 6 pounds.
Explanation
The question wants us to write and solve an inequality that represents how many pounds the parents can add to the shipment without having to pay additional shipping costs.
The towels needed by the student already weigh 9 pounds.
The maximum weight of shipment that is allowable for a payment of $45 is 15 pounds.
Let the additional weight that the parents can add to the shipment without having to pay additional shipping costs be x.
Since the maximum weight allowable is 15 pounds, the 9 pounds already on ground plus the additional x pounds must not exceed 15 pounds. That is, that total weight must always be less than or equal to 15 pounds.
Mathematically,
(9 + x) ≤ 15
This is the inequality equation. We can now solve this
(9 + x) ≤ 15
Subtract 9 from both sides
(9 + x) - 9 ≤ 15 - 9
9 + x - 9 ≤ 6
x ≤ 6
Hence, the number of pounds that the parents can add to the shipment without having to pay additional shipping costs is less than or equal to 6 pounds.
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