Answer:
18 tea bags
Explanation:
A proportion is an equation that shows two ratios as being equal. The ratio of interest here is the ratio of tea bags to gallons. We want it to be the same for any amount of tea. We are given that ratio as being 2 tea bags for 1 gallon of tea.
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The proportion is written ...
bags/gallons = 2/1 = x/9
Multiplying the equation by 9 gives ...
9(2/1) = 9(x/9)
18 = x
18 tea bags are required for 9 gallons.