For certain values of k and m, the system

a + 2b = 2 - 4b - 3a + 7

5a + 2b = k + 5a - mb

has infinitely many solutions (a,b). What are k and m?

From the two equations you have given in the system there is no k and m to get infinite solutions (a,b) could you double check your equations?

4a + 6b = 5

(2 - m) b = k

This only has infinite solutions if both equations are the same......not possible