Answer:
a = -11/4
Step-by-step explanation:
Write an algebraic equation for the slope (using the definition of slope) and set the result = to the given -2/3:
rise 2-(-5) 2
m = ------------- = -------------- = - -------
run -4a - 1 3
Cross-multiply: 3(2+5) = -8a - 1.
Then 3(7) = -8a -1, or 22 = -8a. 22
Dividing both sides by -8, we get a = ---------
-8
or a = -11/4.