Find an equation of the line that goes through the points (-7,46) and (-9,58). write your answer in the form y=mx+b.

First you should know that y=mx+b 

m = slope and b = y-intercept
You should start by finding the slope 

Slope = y2 - y1 / x2 - x1 : (-7,46) and (-9,58) -7 = x1 , 46 = y1 , -9=x2, 58 =y2

58 - 46 / -9-(-7) = 12 / -2  m = -6

Now you need to find y-intercept 

You can pick one of the two coordinates given (-7,46) and (-9,58)

I will pick (-9,58)
y = mx+b , you substitute the values in 

58= -6(-9)+b we have to solve for b or y-intercept 

58= 54 +b
 
b = 4

Answer would be y = -6x + 4