Question -
Answer -
(a) 2(x + 4) = 12
⇒ 
(Dividing both sides by 2) ⇒ x + 4 = 6
⇒ x = 6 – 4 (Transposing 4 to RHS)
⇒ x – 2
Check: Put x = 2 in LHS
2(2 + 4) = 2 × 6 = 12 RHS as required
(b) 3(n – 5) = 21
⇒ 
(Dividing both sides by 3) ⇒ n – 5 = 7
⇒ n = 7 + 5 (Transposing 5 to RHS)
n = 12
Check: Put n = 12 in LHS
3(12 – 5) = 3 × 7 = 21 RHS as required
(c) 3(n – 5) = -21
⇒
(Dividing both sides by 3) ⇒ n – 5 = -7
⇒ n = -7 + 5 (Transposing 5 to RHS)
⇒ n = -2
Check: Put n = -2 in LHS
3(-2 – 5) = 3 × -7
= -21 RHS as required
(d) -4(2 + x) = 8
⇒
(Dividing both sides by -4) ⇒ 2 + x = -2
⇒ x = -2 – 2 (Transposing 2 to RHS)
⇒ x = —4
Check: Put x = -4 in LHS
-4(2 – 4) = -4 × -2 = 8 RHS as required
(e) 4(2-x) = 8
⇒ 
(Dividing both sides by 4) ⇒ 2 – x = 2 – 2 (Transposing 2 to RHS)
⇒ -x = 0
∴ x = 0 (Multiplying both sides by -1)
Check: Put x = 0 in LHS
4(2 – 0) = 4 × 2 = 8 RHS as required