Hello from MrBillDoesMath!
Answer:
r = 4
Discussion:
Slope of a non-vertical line = (change in y values)/(change in x values)
In our case this becomes
slope = -3 =>
-3 = ( r-(-2))/(4 - 6) => as 4 -6 = -2
-3 = ( r+2)/(-2) => multiply both sides by -2
-3(-2) = r+2 =>
6 = r + 2 => subtract 2 from both sides
r = 6 - 2 = 4
Thank you,
MrB
