Răspuns :

Explicație pas cu pas:

a)13,7,20.

13+7=20

7+13=20

20+7=27

7+20=27

20+13=33

13+20=33

13-7=6

20-13=7

20-7=13

b)54,36,18.

54+36=90

36+54=90

36+18=54

18+36=54

54+18=72

18+54=72

54-36=18

54-18=36

36-18=18

c)35,42,77.

35+42=77

42+35=77

42+77=119

77+42=119

77+35=112

35+77=112

42-35=7

77-42=35

77-35=42