in y = mx + b form, the slope will be in the m position (the number right before the x) and the y intercept will be in the b position.
y = mx + b
y = 6x + 4....slope(m) = 6 and y int (b) = 4 or (0,4)
the rest can be done the same way.
On ur last one....y = -2...it is the same as y = -2x + 0