Answer:
155+20n
Explanation:
You start off with the base amount of money, or the constant. That's 155. Then you add 20 dollars per week, depending on how many weeks you are thinking of. That means you need to multiply 20 by the amount of weeks you have been adding money. So 20n. Then you add that to the base amount of money, 155, so the answer is 155+20n