1. The problem statement, all variables and given/known data A customer is choosing between two cellular phone plans. One plan has a monthly fee of $50 for an allowance of 500 minutes per month. If the customer uses more than 500 minutes, the charge is $0.35 per additional minute used. The other plan has a monthly fee of $75 for an allowance of 1000 minutes per month. If the customer uses more than 1000 minutes, the charge is $0.40 per additional minute. After how many minutes used are the monthly costs of the plans equal? 2. Relevant equations This is how I set it up.... Plan 1: (<=500 min) x= $50; (>500 min) x= $50 + $0.35m Plan 2: (<=1000 min) x= $75; (>1000 min) x= $75 + 0.40m 3. The attempt at a solution The answer is 4000 minutes, but I don't know how to proceed. Any help is appreciated.