Answer: The second answer choice
Answer:
A — conclusion: the lines are perpendicular and meet at a 90 angle
Answer:
Step-by-step explanation:
![S_{31} = 9 \cdot 31 + [-0.5 \cdot \frac{31(31-1)}{2}] = 46.5](https://tex.z-dn.net/?f=S_%7B31%7D%20%3D%209%20%5Ccdot%2031%20%2B%20%5B-0.5%20%5Ccdot%20%5Cfrac%7B31%2831-1%29%7D%7B2%7D%5D%20%3D%2046.5)
![S_{40} = 40 + [-3 \cdot \frac{40(40-1)}{2}] = -2300](https://tex.z-dn.net/?f=S_%7B40%7D%20%3D%2040%20%2B%20%5B-3%20%5Ccdot%20%5Cfrac%7B40%2840-1%29%7D%7B2%7D%5D%20%3D%20-2300)
Ann wants to choose from two telephone plans. Plan A involves a fixed charge of $10 per month and call charges at $0.10 per minute. Plan B involves a fixed charge of $15 per month and call charges at $0.08 per minute.
Plan A $10 + .10/minute
Plan B $15 + .08/minute
If 250 minutes are used:
Plan A: $10+$25=$35
Plan B: $15+$20=$35
If 400 minutes are used:
Plan A: $10+$40=$50
Plan B: $15+$32=$47
B is the correct answer. How to test it:
Plan A: $10+(.10*249 minutes)
$10+$24.9=$34.9
Plan B: $15+(.08*249 minutes)
$15+$19.92=$34.92
Plan A < Plan B if less than 250 minutes are used.
Answer: the third one
Step-by-step explanation:
