The cost of a family membership at a health club is $50 per month plus a one time $129 start up fee if a family spent $651 how many months is their membership

Take 651 and subtract that by 129 because that's the one time start up fee. So you end up with 522. Take 522 and divide that number by 50 to find the cost of membership per month. The answer should be 10.44, however, the question asks how many months is their membership, since they didn't pay the full payment of their 11th month, I would say 10 months is their membership.

The percent increase is 25%