The total cost of the gift certificate is $125. You need to buy at least one dress shirt, which costs $28. Therefore, you have $125 - $28 = $97 left to spend on t-shirts.
Now, let's calculate the total cost of t-shirts:
- If you buy no t-shirts, the cost is $0.
- If you buy one t-shirt, the cost is $19.
- If you buy two t-shirts, the cost is $2 × $19 = $38.
- If you buy five t-shirts, the cost is $5 × $19 = $95.
Since you want to leave at most $8 of the gift certificate unspent, you need to check which of the above options are within that limit:
- If you buy no t-shirts and four dress shirts, the total cost is $0 + $28 × 4 = $112, which is within the limit.
- If you buy one t-shirt and four dress shirts, the total cost is $19 + $28 × 4 = $131, which is higher than the limit.
- If you buy two t-shirts and three dress shirts, the total cost is $38 + $28 × 3 = $122, which is within the limit.
- If you buy five t-shirts and one dress shirt, the total cost is $95 + $28 × 1 = $123, which is within the limit.
Therefore, the possible combinations of t-shirts and dress shirts you could buy are:
- No t-shirts and four dress shirts
- Two t-shirts and three dress shirts
- Five t-shirts and one dress shirt