Question

Solve, using the substitution method.

Answer 1

Y - 3x = 7 . . . . . . . . (1)
21 + 9x = 3y . . . . . .(2)
From (1), y = 3x + 7
substituting for y into (2), we have
21 + 9x = 3(3x + 7) = 9x + 21
0 = 0
Therefore, the system has an infinte number of solutions.