Answer:
Explanation: x = number of hours lifeguarding; y = number of hours walking dogs.
Since she can work no more than 13 hours, we will write:
. Also, since she makes $16 per hour lifeguarding (x) and $6 per hour walking dogs (y), and must earn a minimum of $120, we will write:
.
Hence, we have our system written down. To plot the graph, you will need to isolate y in both equations, thus getting:
and

When we plot the graph we get the one in the file attached. So, one possible solution is working 10 hours lifeguarding and 2 hours walking dogs.