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
[tex] S=\frac{n}{2}(2a +(n-1)d) [/tex]
Where a is the first term, n is the nth term, d is the common difference
On substituting there values,we will get
[tex] S =\frac{30}{2}(2*42000+(30-1)1800) [/tex]
= 15(84000+52200) = 15*136200 =2043000
And for company A, it is
[tex] S= \frac{30}{2}(2*45000+(30-1)1500 ) = 15(90000+43500)=2002500 [/tex]
Difference between them =2043000-2002500= 40500
So the correct option is the second option .