Answer:
5 months
Step-by-step explanation:
Let the number of months equalising both plans fee = x
Plan A total fee = 75 + 15x , Plan B total fee = 20 + 26x
Equalise both: 75+15x = 20+26x ; 75-20 = 26x-15x ; 55 = 11x ; x = 55 / 11
x = 5
Proof : 75 + 15 (5) = 20 + 26 (5) ; LHS 150 = RHS 150