Final answer:
To find the percent of markup based on cost, subtract the cost price from the selling price, then divide the markup by the cost price and multiply by 100 to find the percent.
Step-by-step explanation:
To find the percent of markup based on cost, we need to calculate the markup first. Markup is the difference between the selling price and the cost price. In this case, Lilly sells the tea for $12 a box and buys it for $4 a box. The markup is $12 - $4 = $8.
Next, we can calculate the percent of markup based on cost by dividing the markup by the cost price and multiplying by 100. So, the percent of markup based on cost is (8 / 4) * 100 = 200%.