1. what assumptions is mr. jones making about teenagers ?
2. what assumptions is he making about adults?

1. Mr. Jones thinks that teenagers are loud and noisy. They are endlessly talking on phones or with each other, listening to loud music, etc. All of this is annoying for adults who want to have lunch in a quiet place.

He thinks that it is impossible for grown-ups to enjoy lunch where high school students are.

2. As for the adults, Mr. Jones thinks that they need a quiet place to enjoy their meal.

Because adults can have a stressful life or work, they need some nice, quiet place where they can forget about all troubles and just have a break.

That's why he found a great solution to a problem; he decided to create "quiet lunches. From noon till 3 pm, Monday-Friday, the restaurant will be open just for adults, and there won't be any music, cellphones or students.

I hope it helped you :)