[問題]考古題 Form17 sec8 PS-Q11

[凱薩琳]

The long distance telephone rates offered by Company A are 70 percent less for daytime calls amd 20 percent less for evening calls that the corresponding Company B rates, but Company A service charges are $20 per month more that those of Company B. If a business spends $200 per month for daytime calls and $50 per monthe for evening calls with Company B, how much will the business save per month by switching to Company A service?

(A)$80
(B)$100
(C)$120
(D)$130
(E)$150

Ans:D

[StanleyHuang]

題目是說，A公司提供的價錢 白天是 B公司的3折 ，晚上是B公司的8折，但是A公司每個月要多收$20
所以如果原先用B公司的，白天200元，晚上50元的話，換成A公司就會是
200*0.3 + 50*0.8 + 20 = 120 元
所以換成A公司的話就可以省下 250-120=130元

[scujean]

感謝小史

[凱薩琳]

謝謝回答