2/5x - 1 = 9
+1 +1
10
—— ——
2/5 2/5
x = 50
You would need to know the length of two sides either a2, b2, c2. you would also need to know what sides you are solving for, either one of the legs or hypotenuse. hope this helps, if you know how to solve a Pythagorean theorem problem this should be easy to answer

now, a line perpendicular to that one, will have a "negative reciprocal" slope, thus
F(x) = x/4
so
f(-8) = -8/4 = -2
answer
f(-8) = -2
K-263.48=381.09
we add 263.48 on both sides
k=644.57