For what value of m will the system of equations 18x - 72y + 13 = 0 and 7x - my - 17 = 0 have no solution?

Solution (By Examveda Team)

18x - 72y + 13 = 0
7x - my - 17 = 0
There is no solution, means they are parallel
$$\eqalign{ & \frac{{{a_1}}}{{{a_2}}} = \frac{{{b_1}}}{{{b_2}}} \cr & \Rightarrow \frac{{18}}{7} = \frac{{72}}{m} \cr & \Rightarrow m = 7 \times 4 \cr & \Rightarrow m = 28 \cr} $$