Please help

Hint: one way to define no solutions means that when you simplify everything(without possibly dividing by 0, such as 3x=5x, x=0 is a solution), you are left with two unequal numbers equaling each other, such as $3=5$.

Multiply the  first equation by -3

-3x - 3y  - 9z   =   -30

Add this to the  second equation and we get  that

-7x -4z = -22

Mutltiply the  last equation  by  -4

-4kx - 4z  =  -12

The  system will have no solutions when

-4k  =  -7

k =  -7/-4

k  = 7/4

Thanks! Its correct!! :D