Answer:
He must need to work 13 hours or 14 hours for lifeguarding.
Explanation:
Consider the provided information.
Let x represents the number of hours for babysitting.
y represents the number of hours for life-guarding.
In a given week, he can work at most 17 total hours and must

Juan is working two summer jobs, making $12 per hour babysitting and making $16 per hour lifeguarding. He must earn at least $240.

If Juan worked 3 hours babysitting,
Substitute x=3 in



Thus, he can work at most 14 hours for lifegurading.
Substitute x=3 in





Therefore, he must need to work 13 hours or 14 hours for lifeguarding.