Ответ:

1

Объяснение:

5mn-m/4m+n * 16m^2-n^2/5n-1 = (5mn-m)(16m^2-n^2)/(4m+n)(5n-1) = m(5n-1)(4m-n)(4m+n)/(4m+n)(5n-1) = m(4m-n) = 0.25(4*0.25 - (-3)) = 0.25(1+3) = 1