Question 13793
Your first job is to calculate the slope of the line. Because you know two points, you can find the rise between them (difference in y's) and the run between them (difference in x's). A simple division of rise/run gives you the slope. 
{{{(-4.3-4.7) / (4.1 + 3.5) = -9/7.6}}}
So m = -9/7.6
Now you have the equation {{{y = -(9/7.6)x + b}}}
Now find b. We know that when x=0 y=b. So there is a point (the y-intercept) on the y-axis at b. The slope between the points (-3.5, 4.7) and (0, b) is -9/7.6 (the slope is the same everywhere).
So, {{{((4.7-b)/(-3.5-0))= -9/7.6}}}
Solve this for b.
{{{(4.7-b)= -(9)(-3.5)/(7.6)}}}
{{{-b = ((9)(3.5)/(7.6)) - 4.7}}}
{{{b = 4.22/7.6}}} [do the math!]
This gives the equation
{{{y = -((9)/7.6)x + 4.22/7.6}}}
Check this by putting in each value of x and see that you get the correct value for y.