The formula to find the slope of a line is m=(y2-y1)/(x2-x1). In this question: x1=3, x2=2, y1=5, and y2=1. Plug in and solve:
(1-5)/(2-3)=-4/-1=4=m
Slope-intercept form follows the format: y=mx+b, where m is the slope and b is the y-intercept. We calculated m to be 4, so the equation reads:
y=4x+b
To solve for b, you can select one of the ordered pairs (we'll use (2,1)), plug them in for x and y, and solve for b:
1=4(2)+b
1=8+b
-7=b
The equation is y=4x-7.
Hope this helps!!
