Question

(3mn2)+(4m2n2)+(-5mn2)+(-mn2)

Answer 1

6mn+16mn=22mn
-5mn-2mn=-7mn
22mn-7mn=15mn

Answer 2

${3mn}^{2} + {4m}^{2} {n}^{2} - {5mn }^{2} - {mn}^{2} \\ = {3mn}^{2} - {6mn}^{2} + {4m}^{2} {n}^{2} \\ = { - 3mn}^{2} + { {4m}^{2} n}^{2} \\ = {mn}^{2} (4m - 3).........answer$