Răspuns :
a + b = 7
3 x a + 3 x b = 3 ( a + b ) = 3 x 7 = 21
a : 7 = 5 r 7 = > a = 7 x 5 + 7 = > a = 42
3 x a + 3 x b = 3 ( a + b ) = 3 x 7 = 21
a : 7 = 5 r 7 = > a = 7 x 5 + 7 = > a = 42