Question 3 (iii)
Subtract:
(a-b) from (a+b)
(a+b) - (a-b) = a + b - a + b = a - a + b + b = 2b
Question 3 (iv)
a(b - 5) from b(5 - a)
(a) 4ax from 8ax
(b) 7pqr from 12 pqr