SOLUTION
Given the question in the image, the following are the solution steps to answer the question.
STEP 1: Define the revenue function TR
Total revenue is given as:
![Number\text{ of units sold }\cdot Cost\text{ per unit}](https://img.qammunity.org/2023/formulas/mathematics/college/nrdwnmdi6p414u3chvqi8g19852vxx8bhk.png)
By calculation,
Let n represents the number of items sold
![\begin{gathered} By\text{ substitution,} \\ one\text{ item = \$69} \\ TR=69n \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/zbgte7rusfzok1758uh9y3exwiqyrky2v2.png)
Total revenue cost is given as 69n
STEP 2: Define the Total cost function
The formula for total cost is given as:
![\begin{gathered} TC=an+b \\ where\text{ a is the unit cost} \\ n\text{ is the number of items } \\ b\text{ is the fixed cost} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/4s5khnqkti4ozygnuwqi82rv4r3v63ucpv.png)
The known details from the given question are:
![\begin{gathered} a=\text{ \$}9 \\ n=n \\ b=\text{ \$}45000 \\ \\ TC=9n+45000 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/h2fp3sbfqj1zqvcqfvoeste077sc1auw0f.png)
Total cost is given as 9n+45000
STEP 3: Calculate the number of units needed to be sold to break even
Here, we equate TC to TR and this is given as:
![\begin{gathered} TR=TC \\ 69n=9n+45000 \\ 69n-9n=45000 \\ 60n=45000 \\ n=(45000)/(60)=750 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/1uju5oxn7lc6nqzy3bub6hfafhhold6xwb.png)
Hence, 750 units are needed to be sold
STEP 4: Calculate the revenue at the break-even
We get this by substituting 750 for n in the Revenue function
![\begin{gathered} TR=69n \\ n=750 \\ TR=69(750)=\text{ \$}51750 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/kjxkh471svtcb1yddmpimzeumvnanb2m7x.png)
Hence, the TR at the breakeven is $51750