Let x represent the number of months.
The cost of joining the gym is $25.
The cost of the gym membership for each month is $14.
The cost of the gym membership for 6 months can be expressed as:
25 + 14x
Substituting x = 6:
25 + 14(6) = 25 + 84 = $109
Therefore, the cost of the gym membership for 6 months is $109.