5/9m=2+1 1/3
5/9m=3 1/3
m= 3 1/3:5/9
m=10/3*9/5
m=6
3.4n+0,45=3
3.4n=3-0.45
3.4n=2.55
n=2.55/3.4
n=0.75
500м^2=5a
8га=800a
2гa=200a
100м^2=1a
10гa=1000a
1200м^2=12a