To make tea syrup using gallon-size tea bags, the number of tea bags you should use depends on how concentrated you want the syrup to be. Since gallon- size tea bags are designed to brew 1 gallon (128 ounces) of tea, and typically 4 such bags are used for 1 gallon of tea, you can scale down proportionally for 3.5 cups (28 ounces). Calculation:

• 1 gallon = 128 ounces = 4 gallon-size tea bags
• For 3.5 cups (28 ounces), the ratio is 28128=0.22\frac{28}{128}=0.2212828​=0.22 of a gallon
• So, use 4×0.22≈0.884\times 0.22\approx 0.884×0.22≈0.88 gallon-size tea bags, roughly 1 gallon-size tea bag

Recommendation:
Use about 1 gallon-size tea bag to brew 3.5 cups of tea for your syrup. If you want a stronger tea syrup, you can use 1 to 2 bags accordingly. This aligns with common guidelines where 4 gallon-size tea bags brew 1 gallon of tea, so scaling down proportionally works well