Answer: it will take 5 hours for both costs to be equal
Explanation:
Let x represent the number of months for which the cost of the gyms be equal.
Bro Gym charges members $10 per month plus a one time fee of $100 to sign up. This means that the total amount that Bro Gym charges for x hours is
10x + 100
Muscles R' Us Gym charges members $20 per month plus a one time fee of $50 to sign up. This means that the total amount that Muscles R' Us Gym charges for x hours is
20x + 50
For both cost of the gyms to be equal,
10x + 100 = 20x + 50
20x - 10x = 100 - 50
10x = 50
x = 50/10 = 5