Find an equation of the line given one point and the slope. (–10, –5);

You forgot to provide the slope but here is how you do this 

the slope 5 = (y2 - y) / (x2 - x) but we know that (x2, y2) = (-10, -5)
=> (-5 - y) / (-10 - x) = 5 --- multiply both sides by (-10 - x)
=> (-5 - y) = 5 (-10 - x) 
=> (-5 - y) = -50 - (5)x --- add +5 to both sides 
=>  -y = (-50 + 5) - (5)x --- multiply both sides -1 
=> y = 5x + 45  --- this will be your equation.