Question

An electrician earns $110 after his first hour of working for a client. His total pay based on the number of hours worked can be represented using the sequence shown.
110, 130, 150, 170, ...
Which recursive formula can be used to determine the total amount of money earned for each successive hour worked based on the amount of money currently earned?

Answer 1

I don't like trying all of them so I will make up my own which will probably be in the answers 
so equation is
f(x)=pay
x=hours worked
solve so 
f(1)=110
f(2)=130
f(3)=150
f(4)=170

they seem to be increasing in 20 increments so therefor the pay is linked to hours times 20 so that measn that every hour he works, he gets 20 dollars
therefor the answer is f(n+1)=f(n)+20 since we know that 1 hour=$20 so n+1hour=n+$20

the answe ris f(n+1)=f(n)+20

Answer 2

110+20x. $110 is their first hour and gets an additional $20 per hour after the first. 
The variable "x" (which you can substitute for anything) is the number of additional hours they work. You take the number of additional hours worked and multiply that by 20 then add 110 for his first hour.