Răspuns:
Explicație pas cu pas:
6.
Lucrarea este considerata un intreg = 1
Primul muncitor lucreaza intr-o zi 1/12
Al doilea muncitor lucreaza intr-o zi 1/15
Al treilea muncitor lucreaza intr-o zi 1/20
Prima zi 1/12 + 1/15 = 5/60 + 4/60 = 9/60
A doua zi 1/15 + 1/20 = 4/60 + 3/60 = 7/60
In total au lucrat 9/60 + 7/60 = 16/60
Mai au de lucrat 1 - 16/60 = 60/60 - 16/60 = 44/60 = 11/15 din lucrare
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7.
2/3 + 2/15 + 2/35 + 2/63 + 2/99
2/3 + 2/15 = 10/15 + 2/15 = 12/15 = 4/5
4/5 + 2/35 = 28/35 + 2/35 = 30/35 = 6/7
6/7 + 2/63 = 54/63 + 2/63 = 56/63
56/63 + 2/99 = 616/693 + 14/693 = 630/693 = 210/231 = 30/33 = 10/11
