L₁+L₂+L₃=90
L₂-3=L₁+3-1
L₂=L₁+3+3-1
L₂=L₁+5
L₁=L₂-5
L₂-5-15=L₃+5
L₂-20=L₃+5
L₂=L₃+25
L₃=L₂-25
inlocuim ce am aflat in prima relatie:
L₂-5+L₂+L₂-25=90
3L₂=90+30
3L₂=120
L₂=40 mere
Am aflat ca L₃=L₂-25⇒L₃=40-25,deci L₃=15 mere;
Am aflat ca L₁=L₂-5⇒L₁=40-5,deci L₁=35 mere