Answer: 20 times
Explanation:
The total cost must be equal to or less than $130;
$130 ≥
It costs $4 per visit. Let x be the number of visits;
$130 ≥ $4x
There is a $50 fee to join. We will assume it has not yet been paid since you "are joining" the gym;
$130 ≥ $4x + $50
Let us solve for x.
$130 ≥ $4x + $50
$80 ≥ $4x
20 ≥ x
You can go to the gym 20 times this month.