Hi there!
You might already know the first step:
We can find the profit of a company by subtracting the total cost from the total revenue.
Profit = revenue - cost
We can now plug in (substitute) the functions from the question and find the profit function.
Profit = (20X) - (180 + 8X)
Work out the parenthesis. Pay attention to the minus sign in front!
Profit = 20X - 180 - 8X
Collect the terms.
Profit = 12X - 180
P = 12X - 180.
When a company sells breakeven, their total revenue equals their total cost and therefore they have no profit. This leads us to the conclusion that P = 0. Let's solve the equation!
12X - 180 = 0
Add 180 to both sides.
12X = 180
Finally divide by 12.
X = 180 / 12 = 15
Hence, the company must sell 15 bracelets to sell breakeven.
~ Hope this helps you!