35 necklaces multiplied by 4 weeks is 140. Multiply 140 by 15, representing the amount of money each necklace costs and you get 2,100. That is the total amount sold, but because the 6 costumers brought their necklaces back, you have to take 6 times 15 to see how much the total returned necklaces cost. That would be $210, so you take $2,100 and subtract $210, and your answer is $1,180. That is the final answer.
not letting me add answer
Refer to the attachment
Your proof is correct and very well done
Yes, the line passes the vertical line test (no x-values are repeated)