Solve your equation for y:
y = (-8/3)x - 16/3
-8/3 is the slope of that line. A line perpendicular to that given line has a negative inverse slope so the line you want has a slope of 3/8.
Now write the general slope of a line that passes through (-8, -10) and set that slope = 3/8
(y+10)/ (x+8) = 3/8
Solve in y = mx + b form
y+10 = (3/8)(x + 8) = 3x/8 + 3
y = 3x/8 -7 is your line. It has the right slope and y = -10 when x = -8.
This kind of procedure will solve your other two questions too!