how do i write this in explicit formula ?

Question

Math Man gets a jar to start saving money for his family vacation to disney world this year. His vacation is 196 days away so he is sure he can save a lot. He starts by putting 15 dollars in his jar and plans to add 8 dollars to the jar each week. After 5 weeks Math Man wants to know if he has 50 dollars in his jar. Write an explicit formula and determine if math man will meet his goal of 50 dollars by week 5?

Answer 1

a_n = 15 + (n - 1)d

Substitute 5 for n and 8 for d.