Answer:
Yes it is
Step-by-step explanation:
y=-9x means that for every x value, the y value decreases by 9, so it is proportional because the value of y decreases the same amount each time. For example, if x=1, y=-9. If x=5, y=-45, and so on.
11 minutes = 1 km
11 x 5 = 55 minutes
1 x 5 = 5 km.
She can walk 5 km in 55 minutes.
Answer:
8a. 0 8b. -1/3
Step-by-step explanation:
slope formula: 
8a. => (8 + 12)/(17 - 17) = 20/0 = 0
8b. (1 + 2)/(-3 - 6) = 3/-9 = - 1/3