For certain values of k and m the system a + 2b &= -3, \\ a + 2b &= k + 5a - mb has infinitely many solutions (a,b) What are k and m?
a + 2b = -3 multiply through by -4 ⇒ -4a - 8b = 12
Rearrange the second equation as -4a + (2+m) b = k
This system has infinite solutions when
2 + m = -8
m = -10
And
k =12
+617 
