I need help with algebra

Question

To break even in a manufacturing business, income or revenue r must equal the cost of production c. The revenue r from selling x number of computer boards is given by r=80x, and the cost c of producing them is given by c=70x+4000

find how many boards must be sold to be break even.

Answer 1

400 boards must be sold

Since your problem states that to break even, r must equal c

then

r = c

r = 80x

c = 70x + 4000

When

80x = 70x + 4000

Now just solve for x

Give it a try

Answer 2

To break even, Revenue = Cost Plugging in these values:

80x=70x+4000 Subtract 70x from both sides of the equation

80x-70x=70x+4000-70x Simplify

10x=4000 Divide both sides by 10

10x/10=4000/10 Simplify

x=400

Need to sell 400 computer boards to break even.