[tex]y=mx+b[/tex]
(x, y) represents a point the line passes through
m represents the slope
b represents the y-intercept
Plugging in the information you gave...
[tex]7=-2(4)+b[/tex]
If you need to solve for the y-intercept (b)...
[tex]7=-2(4)+b\\7=-8 +b\\15=b\\y-intercept:(0,15)[/tex]
