Răspuns :
xy=10x+y
yx=10y+x
10x+y+10y+x=77
11x+11y=77
11(x+y)=77
x+y=7
Numerele sunt 16, 25, 34, 43, 52, 61
yx=10y+x
10x+y+10y+x=77
11x+11y=77
11(x+y)=77
x+y=7
Numerele sunt 16, 25, 34, 43, 52, 61