Question 1042912
I'll do the first, you do the next one the same way.
{{{5x+4y=8}}}
{{{4y=-5x+8}}}
{{{y=-(5/4)x+2}}}
The slope of this line is {{{m=-5/4}}}.
Now find the slope of the second line.
If they're parallel, 
{{{m[1]=m[2]}}}
If they're perpendicular to each other,
{{{m[1]*m[2]=-1}}}
Else choose neither.