How does y+2=0 rearrange to y=-2? And how do you find a perpendicular line (with a given coordinate)?

a = 0,1

b = 10,6

Equation = y=1/2x+1

Find the equation of the line perpendicular to AB passing through B.

Please explain all in a 'step-to-step' fashion in the simplest way possible including any rearranging equations etc.

I know the answer (y=-2x+26) but, other than the negative reciprocal, I'm not sure how to get it. My answer on the exam was 'y=-2x+6' so I went wrong at the end.

Thanks a lot!