Question

a (a – 4) – a +4.factorise​

Answer 1

Heya mate here is your answer.....
$a(a - 4) - a+ 4 \\ = {a}^{2} - 4 a - a + 4 \\ = a(a - 4) - 1(a - 4) \\ = (a - 1)(a - 4)$
Hope it helps you mate...
Regards !!