you can do it by creating a chart or algebraically

like below

for the members we have

60 (flat fee) + 5 * x (where x represents the number of lessons)

for nonmembers is simple lessons= 11 * x (x represents the number of lessons)

we will set both of these equations equal

60 + 5 * x = 11 * x , we will simplify and get 5x+60=11x

60= 11x-5x , so 60= 6x , x=10

after 10 lessons

x