Answer: linear function is 25x + 20
After 8 weeks he has saved 25(8)+20 which is 200, so he saved $200 after 8 weeks.
Explanation:
Ok so we say 25x because x is any amount of weeks he has saved for and because he had a head start of $20, we add 20 when calculating after any amount of weeks( because even if we know he saved 25x after x weeks we have to add the 20 dollars he also started with)
I hope this helps:)