Question

Mihai si David au împreună 55 cartonase. Mihai si Radu au împreună 77 cartonașe. David si Radu 90 de cartonase
Cate cartonase are fiecare copil?
Corona..

Answer 1

M+d=55
m+r=77
d+r=90

2m+2d+2r=222
m+d+r=111
55+r=111
r=56

77+d=111
d=35

m+d+r=111
m+90=111
m=21

Answer 2

m + d egal 55 cartonase
m + r egal 77 cartonase
d + r egal 90 cartonase
--------------------------------
2m + 2r + 2d egal 222
2(m + r + d)egal 232 / :2
m + d+ r egal 111
55 + r egal 111 /-55
r egal 56
m + 56 egal 77 / -56
m. egal 21
d + 56egal 90
d egal 34