If the slope of a line is -2 and its y-intercept is -7, the equation of the line is:

1. 2x + y + 7 = 0

2. 2x - y + 7 = 0

3. 2x - y - 7 = 0

4. 2x + y - 7 = 0

For the equation x - y + 1 = 0; the values of slope (m) and y-intercept (c) are :

1. m = 1, c = 1

2. m = -1, c = 1

3. m = 1, c = -1

4. m = -1, c = -1