Answer:
6
Step-by-step explanation:
The total of all the angles must be 180, since there is a straight line. We already know the 40 degree angle and the 90 degree angle, meaning that the remaining angle must be equal to 180 - 90 - 40, which is 50 degrees. Therefore, 50 = 7k + 8. 7k = 50-8 = 42, and k = 6.
