6. have been worked                                                                                        7.did you get

x=\(\dfrac{16}{7}\)    y=\(\dfrac{-3}{7}\)

Ơ bạn ơi sáng nay cô mik sửa là 109/100 lận !!

1. Because they have to pay their own fees.

2.He has to work four days a week in the university kitchen.

3. Yes, it is.

4. It helps him build up good experience for his future job.