(3m - 4)(3m + 5n) - (4,5m - n)(2m + 4n)

Question

(3m - 4)(3m + 5n) - (4,5m - n)(2m + 4n)

Answer 1

= 9m^2 +15mn-12m-20n-(9m^2-18mn-2mn-4n^2)=9m^2+15mn-12m-20n-9m^2+18mn+2mn+4n^2=4n^2+35mn-12m-20n