1. 3a-2b+5a-6b-7a+2b=a−6b.

2. 4x2-7y2-6x2 - 4y2+4x2-10y2=2x2 - 21y2.

3. 5a+3b+2c - 2a+3b+2a+4b-11c=5a+10b-9c.
4. x2+3xy-y2+4xy-5y2-2x2+xy-5y2= -x2+8xy-11y2.
5. 12x3-4y3- 5z3 + 2x3 — y3 – z3 – 2y3+x3=15x3 – 7y3 – 6z3.

6. 2a2-3ab+2ac-b2-c2-11ac +7a2+b2=9a2-3ab-9ac- c2.
7. 4a+2a-1-7a-15-a+1+2a+15=0.

8. 5x-2y-3z-3x-4y-2x+6y-32=-6z.

9. 4a-3b-2c2a+7b-4d+3a-4b-5a+4d=-2c.

10. 11x2+4y2-2xy +3y2+2x2 - 3xy -3x2+5xy=10x2+7y2.

11. 7a-{3a+2a-1}=7a-3a-2a+1=2a+1.

12. 8x-6x+2y-12x+3y} =8x-6x-2y+12x-3y=14x-5y. 13. 5x-2y+3x-7y - {6x-2x-5y}

=5x-2y+3x-7y-6x+2x+5y=4x-4y.

=2a-3b+4a-b+2a-6b-b+a=9a-116.

14. 2a- {3b-4a+b} + {2a − 6b −b+a}

15. 3x2- {4xy - 7x2+2xy} - {y2 - 3x2 - 2xy - 4y2}

=3x2 - 4xy+7x2 – 2xy − y2+3x2+2xy +4y2=13x2 – 4xy+3y2.

16. 2x2-x2+x-1-3x+4+2x2+12x-1+6x=3x2+16x+2.

17. x3-3x2+2xy +4y2 − x − x2+4-4x2+3x-1= −7x2+2xy +2x+4y2+3.

18. 7x2+2x2-3x-9+ {x2 -5x+7-x2 - 3x} +12=9x2-11x+10.