(10a+b) + (10c+d) = 47
10(a+c)+(b+d)=47
y = 47- 10x
(10b+a) + (10d+c) = 173
(a+c)+10(b+d)=173, notam a+c = x si b+d = y
x + 10y = 173
x+10(47-10x) = 173
x + 470-100x=173
297 = 99x
x = 3
a+c=3,
a=1 si c=2
y = b+d =17 , b,d<=9
b=8 si d=9
Numerele sunt 18 si 29.
