Find the equation of the line that is perpendicular to y=3y-x=7 and contains the point (2,-1).

First you want to get it into standard form. which would mean you get the x of the side of the y and divide everything by the y's coefficient in this case 3.

3y-x=a

3y=x+a

y=1/3x+a

Now your going to want to turn this into a perpendicular li e which means you flip the coefficient and make it negitive

y=-3x+a

then we fill in the points.

-1=-3(2)+a

Solve

-1=-6+a

-1+6=a

5=a

Now put it in standard form.

y=-3x+5