Answer:
X= -3
Step-by-step explanation:
Distance traveled in 3 hrs was (speed in mph)(3 hrs)
Then s(3 hrs) + 12 mi = 132 mi.
Therefore, 3s = 120, and s = 120 miles / 3 hrs = 40 mph (answer)
The square of a binomial expands as follows:

Expanding all the binomials, we have

Sum like terms:

Simplify terms appearing on both sides:

Move all terms involving k to the left and all numbers to the right:

Divide both sides by -20:

Hopes this helps:
Answer: -3/8
Have a great day.