the first step is to turn the line into standard form.
2x+5y=7
7-2x=5y
7/5-(2/5)x=y
the secound step is making it a perpendicular line. the way you do this is by multiplying the coefficient by -1. then you would flip the fraction over. and writing it in standard form with a being the constant.
(5/2)x+a=y
now you fill in the points.
(5/2)(0)+a=7
solve
0+a=7
a=7
the full equation will now be.
(5/2)x+7=y
