we have the equations of the lines
Line 1
10x+4y=-8
isolate the variable y
4y=-10x-8
y=-(10/4)x-8/4
y=-2.5x-2
Line 2
2y=-5x+7
isolate the variable y
y=-(5/2)x+7/2
y=-2.5x+3.5
Line 3
y=-(5/2)x-6
y=-2.5x-6
Remember that
If two lines are parallel, then their slopes are equal
In this problem
The three lines have the same slope (slope m=-2.5)
that means
the three lines are parallel
the answer is
Line 1 and Line 2 ----> parallel
Line 1 and Line 3 ----> parallel
Line 2 and Line 3 ---> parallel
