The system of equations has 3 cases
1. y = ax + b, y = ax + c
Since the coefficient of x and y are the same, and the y-intercepts are different, then
The two lines are parallel
2. y = ax + b, y = dx + c
Since the 2 lines have different coefficients of x, then
The two lines are intersected
3. y = ax + b, y = ax + b
Since the two lines have equal coefficients of x and equal y-intercepted, then
The two lines are coincide (same line)
6. a)
Since the system of equations is
The coefficients of x not equal
Then from case 2 above
The two lines are intersected
6.b
Since the system of equations is
The coefficients of x are equal
The y-interceptes not equal
Then from case 1 above
The two lines are parallel