(i) 3x - 5 - x + 9

=3x - x - 5 + 9

= 2x - 5 + 9

= 2x + 4

Put x = 3

= 2(3) + 4

= 6 + 4

=10 Ans.

(ii)2 - 8x + 4x + 4

= -8x + 4x + 2 + 4

= -4x + 2 + 4

= -4x + 6

Put x = 3

= -4(3) + 6

= -6 Ans.

(iii) 3a + 5 - 8a + 1

On rearraning the terms,

= 3a - 8a + 5 + 1

= -5a + 5 + 1

= -5a + 6

Put a = -1

= -5(-1) + 6

= 5 + 6

= 11 Ans. 

(iv) 10 - 3b - 4 - 5b

= 10 - 4 - 3b - 5b

= 6 - 3b - 5b

= 6 - 8b

Put b = -2

= 6 - 8(-2)

= 6 + 16

= 22 Ans. 

(v) 2a - 2b - 4 - 5 + a

On rearranging the terms, 

= 2a + a - 2b - 4 - 5

= 3a - 2b - 4 - 5

= 3a - 2b - 9

Put a = -1 & b = -2

= 3(-1) - 2(-2) - 9

= -3 + 4 - 9

= -8 Ans.