Question bank / Linear inequalities in one or two variables

Math · AlgebraHard

A store sells shirts for $12\$12 each and hats for $8\$8 each. A customer wants to buy at least 1010 items and spend no more than $100\$100. What is the maximum number of shirts the customer can buy?

A

55

B

66

C

88

D

1010

Show answer and explanation

Answer: A

Let ss be shirts and hh hats: s+h≥10s + h \ge 10 and 12s+8h≤10012s + 8h \le 100. To maximize shirts, buy the fewest hats possible, h=10−sh = 10 - s. Then 12s+8(10−s)≤10012s + 8(10 - s) \le 100, so 4s+80≤1004s + 80 \le 100 and s≤5s \le 5. Five shirts and five hats cost exactly $100\$100.

Choice C is the most shirts the customer could afford with no hats, but then the customer would buy only 8 items, not at least 10.

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