Here are the prices of two gyms:
• gym a has a membership fee of $30 plus $5 per month for every month you are a member of the gym
• gym b has no membership fee but charges $10 per month for every month you are a member of the gym

if you were two join gym a, at least how long would it take before you are paying less than gym b ?
a. 5 months
b. 6 months
c. 7 months
d. 8 months