57. 4795-!-item-!-187;#058&004223
During a sale, for each shirt that Mark purchased at the regular price, he also purchased a shirt at half the regular price. How many shirts did Mark purchase during the sale?
(1) The regular price of each of the shirts that Mark purchased during the sale was $21.50.
(2) The total of the prices for all the shirts that Mark purchased during the sale was $129.00.
答案是C,我是選E
我是想請問,因為題目是問how many....
但是這邊算出來可能有7,8,9,10,11這些可能
也算是成立嗎??
21.5x+10.75y=129
2150x+1075y=12900
當y=2,x=5 y=8,x=2
y=4.x=4 y=10,x=1
y=6,x=3