<u>Step</u><u> </u><u>1</u>
given
<u>Step</u><u> </u><u>2</u>

<u>Step</u><u> </u><u>3</u>

Reason: Reflexive property
<u>Step</u><u> </u><u>4</u>
ASA
Substitute the given values for the parameters in the point-slope form of the equation of a line. That form is
y - k = m(x - h)
for point (h, k) and slope m.
You have (h, k) = (1, 2) and m=-3, so your equation is
y - 2 = -3(x - 1)