Christopher is deciding between two different movie streaming sites to subscribe to. Plan A costs $31 per month plus $0.50 per movie watched. Plan B costs $7 per month plus $2 per movie watched. Let AA represent the monthly cost of Plan A if Christopher watches xx per month, and let BB represent the monthly cost of Plan B if Christopher watches xx movies per month. Write an equation for each situation, in terms of x, commax, and determine the number of monthly movies watched, x, commax, that would make the two plans have an equal monthly cost.