Răspuns:
36-42:e:(5-4)-20=10
36-42:e:1-20=10
36-42:e:1=20+10
36-42:e:1=30
42:e:1=36-30
42:e:1=6
e:1=42:6
e:1=7
e=7×1
e=7
36-42:e:(15:3-4:1)-20=10/+20
36-42:e:(15:3-4:1)=30+42
36:e:(15:3-4:1)=72:36
e:15:3-4:1=2/×1
e:15:3-4=2/+4
e:15:3=6/×15:3
e=6×5
e=30.
Sper că te-am ajutat!
Explicație pas cu pas:
Am folosit mersul invers.
