Răspuns:
Explicație pas cu pas:
c) ab=10a++b
ba=10b+a
ab+ba=10a+b+10b+a=11a+11b=11(a+b)
(ab+ba):11=11(a+b):11=a+b
d) ab-ba=10a+b-10b-a=9a-9b=9(a-b)
(ab-ba):9=9(a-b):9=a-b
2)abcabc=100000a+10000b+1000c+100a+10b+c= 100100a+10010b+1001c
abc00=10000a+1000b+100c
abcabc+abc00=100100a+10010b+1001c+10000a+1000b+100c=
= 110100a+11010b+1101c= 1101*(100a+10b+c)
abc=100a+10b+c
(abcabc+abc00):(3*abc)= 1101*(100a+10b+c):(3*(100a+100b+c))=367
