Kaj is working two summer jobs, making $13 per hour lifeguarding and making $7 per hour washing cars. In a given week, she can work at most 15 total hours and must earn a minimum of $140. Also, she must work no more than 11 hours lifeguarding and a maximum of 4 hours washing cars. If a represents the number of hours lifeguarding and y represents the number of hours washing cars, write and solve a system of inequalities graphically and determine one possible solution.​