(11)
we are given two points 
(x1,y1)=(0,3)
(x2,y2)=(8,7)
so, we get 


(a)
we know that slope of parallel lines are always equal 
so, we can use formula 

now, we can plug values


............Answer
(b)
we know that slope of perpendicular line is -1/m
so, 

now, we can plug value

...............Answer
(12)
we are given two points 
(x1,y1)=(5,-1)
(x2,y2)=(3,1)
so, we get 


(a)
we know that slope of parallel lines are always equal 
so, we can use formula 

now, we can plug values


............Answer
(b)
we know that slope of perpendicular line is -1/m
so, 

now, we can plug value

...............Answer