Answer:
10%
Step-by-step explanation:
We have been given that the manager of a store orders model railroad sets that cost $390 and sells them for $429.
We will use markup % formula for our given problem.





Therefore, markup is 10% of cost.
The 6 is a positive and the 2 is a negative. Basically the answer to the equation would be a negative
6 x -6 = -36
Hope this helps you
-AaronWiseIsBae
Answer: The answer would be C
Explanation: I am taking the test right now and that answer is the only one that would make sense. I apologize if I am wrong.