Explicație pas cu pas:
abc= 5bc+6c
100a+10b+c= 5(10b+c)+6c
100a+10b+c= 50b+5c+6c
100a-40b-10c= 0/:10
10a-4b+c= 0,
10a, 4b sunt nr. pare, deci c trebuie sa fie par
c= 0, 10a= 4b/:2, 5a=2b, a=2, b= 5
abc= 250,
c=2, 10a-4b+2= 0/:2, 5a-2b+1= 0, a=1, b= 3
abc= 132
5a-2b+1= 0, a= 3, b=8,
abc= 282
c=4, 10a-4b+4=0/:2, 5a-2b+2= 0
a= 2, b= 6
abc= 264
c=6, 10a-4b+6=0/:2* 5a-2b+3=0
a= 1, b= 4
abc= 146
a=3, b= 9
abc= 396
c=8, 10a-4b+8=0/:2, 5a-2b+4= 0
a= 2, b= 7
abc= 278
