Don't know try something else it will probably help
1) yes
2) no
3) a. yes
b. no
3) you have two question #3's...
4) Do your own homework
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 .
Answer:
0.0335mm to 0.0345mm
Step-by-step explanation: