(a+b)(4-m)-(3a-4b)(m-4)

Question

(a+b)(4-m)-(3a-4b)(m-4)

Answer 1

(a+b)(4-m)-(3a-4b)(m-4)
=4a-am+4b-bm-(3am-12a-4bm+16b)=
=4a-am+4b-bm-3am+12a+4bm-16b=
=16a-4am-12b+3bm