Answer: For 2 months is the cost of the clubs equal.
Explanation:
Let the month be 'x'.
In case of one health clubs:
Amount for sign up fee = $50
Amount per month = $65
So, the equation becomes,

In case of another clubs:
Amount for sign up fee = $90
Amount per month = $45
So, the equation becomes

According to question, we get that

Hence, for 2 months is the cost of the clubs equal.