Frank joined a fitness club. he paid a $50 registration fee, and dues are $12 per month. which expression can be used to find the average monthly cost of an x-month membership at the club?

12x+50

explanation:

we know that x is the number of months.   frank pays $12 per month; this gives us 12x.

we also know that frank paid a $50 registration fee.   this would be added on to the monthly costs, giving us

12x+50

or

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