Răspuns :
(a+a+1+a+2):7=13 rest 5
3a+3=7×13+5
3a+3=91+5
3a=91+5-3
3a=91+2
3a=93
a=31
a+1=31+1=32
a+2=31+2=33
3a+3=7×13+5
3a+3=91+5
3a=91+5-3
3a=91+2
3a=93
a=31
a+1=31+1=32
a+2=31+2=33