for plan 1, since she would have to pay $3 per visit and x is the visits per month, than you would calculate the total cost per visits by 3x. and since there is a starting fee of $50, the total goes up from 50 and never below, therefore 50 is the y-intercept
plan 2, its the same thing as plan 1 but instead of $3 per visit it is $10 and there is no starting fee, so no y-intercept
