Răspuns:
(a+a+1+a+2+a+3+a+4+a+5+a+6) : 5=18 rest1
(7a+21) : 5=18 rest1
7a+21=5 x 18+1
7a+21=90+1
7a+21=91
7a=91-21
7a=70
a=70:7
a=10
a+1=10+1=11
a+2=10+2=12
a+3=10+3=13
a+4=10+4=14
a+5=10+5=15
a+6=10+6=16
verificare:
10+11+12+13+14+15+16=91
91:5=18 rest1
Explicație pas cu pas:
