Plug it into point-slope form.
y - y1 = m(x - x1)
Where y1 is the y-value of the point, x1 is the x-value, and 'm' is the slope.
So plug in -1 for x1, 2 for y1, and 0.9 for 'm':
y - 2 = 0.9(x + 1)
Simplify to get in slope-intercept form:
Distribute 0.9 into the parenthesis:
y - 2 = 0.9x + 0.9
Add 2 to both sides:
y = 0.9x + 2.9