Hi,
Answer:
k = 
Step-by-step explanation:
Subtract 4k from both sides
6k - 4k = 2k
2k - 8 = 15
Add 8 on both sides (you want to get rid of the 8 in order to leave the k alone)
2k = 23
k = 23/2
Have a good day!

The last choice is appropriate.
Yes . When you do the line test you go straight done and it doesn’t have 2 points on the same line .
Answer:
The price elasticity of demand is calculated as the percentage change in quantity divided by the percentage change in price.