Answer
$y-15=5(x-3)$
Work Step by Step
RECALL:
(1) The point-slope form of a line's equation is $y-y_1=m(x-x_1)$ where $m$=slope and $(x_1, y_1)$ is a point on the line.
(2) The slope-intercept form of a line is $y=mx+b$ where $m$=slope and $(0, b)$ is the line's y-intercept.
With $m=5$ and $b=15$, substituting these into the slope-intercept form of a line gives:
$y=5x+15$
To convert the equation above into point-slope form, subtract 15 to both sides of the equation to obtain:
$y-15 = 5x-15$
Factor out $5$ on the right side of the equation to obtain:
$y-15=5(x-3)$