Answer:
Martha is incorrect.
Amount paid by Renee = 

Amount paid by Susan = $297.5
Amount paid by Martha = 

Explanation:
Given: Renee will pay 40% of the cost. Susan will pay 0.35 of the cost.Martha will pay the remainder of the cost. Martha thinks she will pay 13 of the cost.
To find: Is Martha correct? 
To find: amount paid by each of Renee, Susan, and Martha
Solution:
Percentage of an amount paid by Renee = 40% 
Percentage of an amount paid by Susan = 35%
So,
Percentage of an amount paid by Martha = 

But Martha thinks she will pay 13 of the cost. So, she is incorrect.
Amount paid by Renee = 

Amount paid by Susan = 

Amount paid by Martha = 
