Brad and Mona are comparing the international calling plans on their cell phones. On his plan, Brad pays $4 just to place a call and $4 for each minute. When Mona makes an international call, she pays $1 to place the call and $5 for each minute. A call of a certain duration would cost the exact same under both plans. What is the duration? What is the cost? A call of minutes would cost $ under each plan