Are the two lines parallel?

Are the two lines parallel?
2x - y = 1
    and
2y - 4x = 7

Parallel lines have equal slopes. 

Slope-intercept form is y = mx + b
m is the slope
b is the y-intercept 

2x - y = 1
-y = -2x + 1 {subtracted 2x from each side}
y = 2x - 1 {divided each side by -1}
slope is 2 

2y - 4x = 7
2y = 4x + 7 {added 4x to each side}
y = 2x + (7/2) {divided each side by 2}
slope is 2 

Slopes are equal. The lines are parallel.
 
As shown by using the graphing calculator:

 - Algebra House