please help with this

Answer:
5/8
Step-by-step explanation:
Line f passes through the points (10, 7) and (5, 15)
Slope of line f = (15 - 7)/(5 - 10) = 8/(-5) = -8/5
line g is perpendicular to line g.
slope of line g = -1/(slope of line f)
=-1/(-8/5)
= 5/8