Corina si Diana au sadit inpreuna 67de panselute.Corina a sadit cu 17 panselute mai mult decat Diana.Cate panselute a sadit fiecare fată ?

Răspuns :

C+D=67
C=D+17

inlocuim necunoscutele:
D+17+D=67
2D+17=67
2D=67-17
2D=50
D=50:2
D=25 panselute

C+25=67
C=67-25
C=42 panselute

proba: 42+25=67 
Diana I----I
Corina I----I-17-I

Egalam panselutele
67-17=50
Cate panselute are Diana 
50÷2=25
Cate panselute are Corina 
25+17=42 

Proba:

42+25=67
42-25=17