Math 7 Exercise 1&1* page 20

 $9ab-5ab=....$  

 $5xy+2yx=....$  

 $7cd-8cd+3cd=....$  

 $3ba-ab+3ab-5ab=....$  

 $4gh-5jk-2gh+7=....$  

 $12ab-6ba+ba-7ab=....$  

 $7xy+5xy-13xy=....$  

 $4ab+10bc-ba-7cb=....$  

 $4pq-7qp=....$  

 $2xy+y-3xy=....$