Răspuns :
a=7k din cmmdc=7 7 I a
b=7t 7 Ib
ab = 7k·7t= 980
49·kt=980
k·t=980 :7=49= 20
k 1 2 4 5 10 20
-------------------------------------------------------------------------------------------
t 20 10 5 4 2 1
a=7 ; b=140
a=14 b=70
a=28 b=35
a=35 b=28
a=70 b=14
a=140 b=7
b=7t 7 Ib
ab = 7k·7t= 980
49·kt=980
k·t=980 :7=49= 20
k 1 2 4 5 10 20
-------------------------------------------------------------------------------------------
t 20 10 5 4 2 1
a=7 ; b=140
a=14 b=70
a=28 b=35
a=35 b=28
a=70 b=14
a=140 b=7