.035 is the answer to your question
160/4=40 so each side is 40. Divide the perimeter by how many sides you have.
They are parallel. the second one is just translated up by 5.
Y = 3000x + 28000
y = 2800x + 30000
3000x + 28000 = 2800x + 30000
200x = 2000
x = 10
The salaries will be the same after 10 years.