Did you notice that, in the first problem, the coefficient of x in the first equation is 4 and in the second equation it is 8. That coefficient has been multiplied by 2! The coefficient of y in the first equation is -3. In order to be parallel (have the same slope as Subhotosh Kahn suggested) that must be multiplied by 2 also.
In the second problem, the coefficient of x in the first equation is 2 and in the second equation it is 4. What has it been multiplied by? The coefficient of y in the first equation is -7. What must it be multiplied by to make the lines parallel?