I zi /............./................/............../________/______/______/_____/________/
II zi R₁/..../...../...../...../__/__/__/__/__/__/__/_/_/__/__/
III zi R₂ /________₅₅₀______________/
11 parti=550
1 parte=550:11=50
R₂=50X15=750
a II-a zi =50x4=200
suma =(750:5)x8=150x8=1200
I zi=150x4=450