Write the equation of the line with this given information in slope intercept form

We have the following:
The equation of a line in its slope and y-intercept form is as follows
[tex]y=mx+b[/tex]where m is the slope and b is the y-intercept:
now,
When two lines are perpendicular, the product of their slopes is equal to -1
[tex]\begin{gathered} m_1\cdot m_2=-1 \\ 3\cdot m_2=-1 \\ m_2=-\frac{1}{3} \end{gathered}[/tex]now, for b, replacing
x = 15 and y = 2
m = -1/3
[tex]\begin{gathered} 2=-\frac{1}{3}\cdot15+b \\ 2=-5+b \\ b=2+5 \\ b=7 \end{gathered}[/tex]The equation is:
[tex]y=-\frac{1}{3}x+7[/tex]