Answer:
Given,
The jewelry business orders $ 1320 in supplies each month.
That is, the invested amount = $ 1320,
Also, the selling price of each earring/ring set = $ 55,
Part 1 : Let x be the number of set that have been sold each month to break even ( in which revenue and invested amount are equal )
So, Total revenue ( the cost of x sets) = 55x,
⇒ 55x = 1320
Divide both sides by 55,
We get,
x = 24
Hence, 24 sets are needed to sell each month to break even.
Part 2 : Let y be the number of sets in which the profit is $ 715,
Total revenue = 55x
Profit = Total revenue - invested amount
⇒ 55x - 1320 = 715,
⇒ 55x = 715 + 1320
⇒ 55x = 2035
⇒ x = 37
Hence, 37 sets are sold for the total profit of $715.
Part 3 :
Revenue in selling 7 sets = 55 × 7 = $ 385
Profit = $ 385 - $ 1320 = - $ 935
Hence, the profit is - $ 935 after selling 7 sets.