The fish market sell 16 pound of fish and 12.5 pound of lobster.
[ (12 - n)/7 ] = -1
12- n = -7
-n = -19
n = 19
Answer: D.
You can get the lowest price at Store C
The expression in company B represents that is is in arithmetic progression where first term is 42000 and common difference is 1800 . So we have to use the formula of sum of n terms which is

Where a is the first term, n is the nth term, d is the common difference
On substituting there values,we will get

= 15(84000+52200) = 15*136200 =2043000
And for company A, it is

Difference between them =2043000-2002500= 40500
So the correct option is the second option .