[tex]\sf~y-y_1=m(x-x_1)[/tex]
Where y1 is the y-value of the point, x1 is the x-value, and 'm' is the slope.
In this case:
y1 = -7
x1 = 1
m = -2/3
Plug them in:
[tex]\sf~y-(-7)=-\dfrac{2}{3}(x-1)[/tex]
or
[tex]\boxed{\sf~y+7=-\dfrac{2}{3}(x-1)}[/tex]
