Помогите упростить 4/9:(2,7m-2 1/4n)-4,2*(5/7m-0,5n)

4/9(2,7m-2.1/4n)-4,2(5/7m-0,5n)=-1,8m+1,1 n1) (4/9*27/10m-4/9*9/4n)=6/5m-n2) 4,2*(5/7m-0,5n)=21/5*5/7m-21/5*1/2n=3m-21/10n3) 6/5m-n-3m+2,1n=1,2m-3m-n+2,1n=-1,8m+1,1n