a) Since parallel lines have the same slope, the slope will be `4`.

b) Using m_{1} × m_{2}= -1, with m_{1} = 4, we obtain the value for m_{2}:

`m_2=-1/(m_1)` `=-1/4`

`m_2=-1/(m_1)`

`=-1/4`

Easy to understand math videos: MathTutorDVD.com