Are the lines y = –x – 4 and 5x + 5y = 20 perpendicular? explain.

yes; their slopes are equal.
yes; their slopes have product –1.
no; their slopes are not equal.
no; their slopes are not opposite reciprocals.

No the slopes are not equal. 

No the slopes are not equal. 

Actually no, they are not perpendicular because they both have a negative slope. We know this when we plot points (x,y) to see y= -x-4 5x+5y=20
Please give it a check by this sucession of numbers
( -1, -3 ) (-1, 5 ) 
( 0, -4 ) ( 0, 4 ) 
( 1, -5 ) ( 1, 3 ) 
( 2, -6 ) ( 2, 2 ) 
( 3, -7 ) ( 3, 1 ) 
( 4, 8 ) ( 4, 0 ) 
( 5, -9 ) ( 5, -1 ) 
I hope this helped you

Actually no, they are not perpendicular because they both have a negative slope. We know this when we plot points (x,y) to see y= -x-4 5x+5y=20
Please give it a check by this sucession of numbers
( -1, -3 ) (-1, 5 ) 
( 0, -4 ) ( 0, 4 ) 
( 1, -5 ) ( 1, 3 ) 
( 2, -6 ) ( 2, 2 ) 
( 3, -7 ) ( 3, 1 ) 
( 4, 8 ) ( 4, 0 ) 
( 5, -9 ) ( 5, -1 ) 
I hope this helped you

The answer should be 3%