Concept: The question tests on the application of Profit/Loss Concepts.
Solution:
It is given that for every 60 cameras 54 make a profit and 6 make a loss.
=> 54/60 =9/10 cameras contribute to profit whereas 1/10 contributes to a loss.
Let there be 10 cameras priced at $10 each
=>Total investment =10*10=100$
Total profit =(20% of 10)*9 =18$
Total loss = (50% of 10)*1 =5$
Hence effective profit = 18-5 =13 $
Profit% = Profit/CP(Investment)*100
= 13/100)* 100 =13 % profit. (Option D)