"part a: solve −np − 70 < 40 for n. show your work."

"part b: solve 4w − 7k = 28 for k. show your work."
i get confused with these types of questions . someone !

Given :Cost function :

To Find : Find the average cost per item when the required number of items is produced

Solution:

a) 200 items

Cost function :

Substitute x = 200

So, Total cost of producing 200 items is 12320

Now Average cost per item =

Average cost per item=

Average cost per item=61.6

So,  the average cost per item when 200 items are produced is 61.6 .

b) 2000 items

Cost function :

Substitute x = 2000

So, Total cost of producing 2000 items is 26000

Now Average cost per item =

Average cost per item=

Average cost per item=13

So, the average cost per item when 2000 items are produced is 13.

c) 5000 items

Cost function :

Substitute x = 5000

So, Total cost of producing 5000 items is 48800

Now Average cost per item =

Average cost per item=

Average cost per item=9.76

So, the average cost per item when 5000 items are produced is 9.76