Card 1
$0.50 + $0.02x = y
Card 2
$0.25 + $0.03x = y
Card 1: Charges $0.50 and adds 2 more cents for each minute
Card 2: Charges $0.25 and adds 3 more cents for each minute
$0.50 + $0.02(25) = $1.00
$0.25 + $0.03(25) = $1.00
At 25 minutes the cards charge the same amount of $1.00 .