5,6z - 2z - 0,7z + 2,65 =7
5,6z-2z-0,7z+2,65=7
2,9z+2,65=7
2,9z=4,35
z=1,5
z (5.6-2-0.7) = 7-2.65
2.9 z = 4.35
z=4.35/2.9=1.5