Răspuns:
Explicație pas cu pas:
fluturi + albine = 34
buburuze + albine = 26
fluturi + buburuze = 30
___________
2 x fluturi + 2 x albine + 2 x buburuze = 34 + 26 + 30
2 x (fluturi + buburuze + albine) = 90
fluturi + buburuze + albine = 90 : 2 = 45
buburuze = 45 - 34 = 11
fluturi = 45 - 26 = 19
albine = 45 - 30 = 15