1.a) 6x+5y–3x

b) 4a–3b+12–(4a+3b)

2.a) 9x–(5y+x)–y

b) 5x–26–(4x–3)

3.a) 7a–(–3b+2a)+l0b

b) (5a+3b)+(6x–3b)

4.a) 4m+7n–(–5m+8n–23)–23

b) 7z–13–(18y+8z–13)+8y

5.a) 62x–9y–(41x–11y)–(x–18y)

b) 6x–[(3x+2y)+2x]–(8x+9y)

6.a) (3x–4y)–[5y+(7y–2x)–(8x–y)]

b) 10x+[(7y–12x)–(5y+12x–13)]–13

7. 5c+15b+6a–[3b–(8b+4a)–17a+12b–13c–(7a+2b–23c)]

8. a) –a–(–b)+{–3a–[–7+(2a–3b)]}

b) 5x+7y–{3z+[13x–(2y+7x)]–7z}

9. a) 5s+10t–{–[–(8s+9t)]–7s+(–8t)}

b) 3u–4v–{[5u–(3v+2u)–6v]+8u}

10.a) 2c–3d–{–5c–[–(6c–7d)+c]–2d}

b) 3a+7b–(–7a+13b–(–11a+12b+(13a–2b)))

11. 16m+(3n–(4m–3n–(16m–3n)))–(7n+3m)

12. 8x–{9y–[10z–(11x–12y)]–(13z–3x–y)}

13. –12a +((6b–(90a+ 12b)) –(16b+ 80a)) + (25a + 10b)

14. 3f –7g – {–(3f–2g) –[(3g + 8f) –2g]–[(7g– 8f) +2g]}

15. 4x–(5y+(3y–(8x–14y+21z)–(21y–27z)+23x)+10y)

16. 5a–[(6b–7a)–(8a–9b)]–10b–{10a+[(11a–12b)–(13b+22a)]}

17. 6a+{4a–[–14b–(2a+4b)]–7b} – {7b+[9a–(11b+4a)]+6a} –(7b–8a)