What is the equation of the line that passes through the points (1,2/3)
what is the equation of the line that passes through the points (1,2/3) and (-1,-1)?

First find the slope
the slope/gradient formula is
(y₂ - y₁) = m(x₂ -x₁)
y₂ = -1                       y₁ = 
x₂ = -1                       x₁ = 1
Plug them in
(-1 - ) = m(-1 - 1)
= m(-2)
Divide by -2
= 
-2 and -2 cancels out
= m
So we found the slope, now apply the ones we know to the equation of the line which is:
          y = mx + c
Take any of the 2 coordinates
-1 = -(-1) + c
-1 = 
Take the fraction to the other side
-1 -  = 
fraction cancels out
= c

Equation of that line is:
y = 

Agc and bgd are vertical angles