Ginger is selling gym memberships. The first week she sold 5 memberships and each week for the next four weeks she sells 3 more than the previous week. After 5 weeks, how many memberships has she sold?

You can solve this in a long way so that you will understand the relationship of the increase in the number of memberships sold.

First week = 5 memberships

Second week = 8 memberships (5 + 3)

Third week = 11 memberships (8 + 3)

Fourth week = 14 memberships (11 + 3)

Fifth week = 17 memberships (14 + 3)

Total after 5 weeks = 55 memberships sold (5 + 8 + 11 + 14 + 17)