Answer:
r = 3x
Step-by-step explanation:
Along with any equation you write, you must define your variables. Here, you are asked to represent earnings based on how many you sell. This leads us to presume that the number you sell will need to be represented by a variable, and the equation will give the amount of earnings for that number sold.
Revenue is the product of the number of items sold and the price at which they are sold. If you sell x items at a price of $3, your revenue (r, in dollars) will be ...
r = 3x
_____
The domain of this equation is 0 ≤ x ≤ 50 if you have a maximum of 50 items you can sell.
_____
Comment on earnings
"Earnings" is synonymous with profit, which is the difference between revenue and cost. There is not enough information in this problem statement to make an assessment of earnings. We can only describe revenue.
