Даю 25 баллов 1 вопрос пожалуйста.
(6; 9) = (x; y)
{ax-3y = 12
{5x+by = 21
1)ax-3y = 12
6a-27 = 12
6a = 39
a = 39/6 = 13/2 = 6.5
2)5x+by = 21
30+9b = 21
9b = -9
b = -1
