equation of a line with y intercept of neg.2 is y=mx-2
you could use pint slope[y-y1=m(x-x1)], but i preffer slope intercept form [y=mx+b]
5=m2-2
move 2 to the other side
7=m2
divide both sides by 2
3.5=m
so, the slope is 3.5
equation for a line that passes through point (2,5) with a y intercept of -2 is y=3.5x-2
the equation of a perpendicular line to the line y=3.5x-2 has a slope that is negative reciprical of 3.5
we keep the everything on y=3.5x-2 same except the slope.
negative reciprical slope of 3.5 is -

simplify

so, the equation of a line perpendicular to the first one is y=-2/7x-2