Lydia is deciding between two different movie streaming sites to subscribe to. Plan A costs $5 per month plus $2.50 per movie watched. Plan B costs $24 per month plus $1.50 per movie watched. Let A represent the monthly cost of Plan A if Lydia watches : per month, and let B represent the monthly cost of Plan B if Lydia watches z movies per month. Write an equation for each situation, in terms of x, and determine which plan would be cheaper if Lydia plans on watching 21 movies each BE - iss cheaper than when watching 21 movies.​