Suppose that Dave has $200 to spend per week and he buys only magazines and pizza. The price of a pizza is $10 and the price of a magazine is $5. If Dave buys 20 magazines per week, which of the following amount of pizza is not affordable to him?
A.
10
B.
20
C.
9
D.
All of the above answers are correct because none of the listed amounts of pizza are affordable.
【简答题】某乳品公司向某地运输一批牛奶,由铁路运输每千克需运费 0.58 元,由公路运输,每千克需要运费 0.28 元,另需补助 600 元。 ( 1 )设该公司运输的这批牛奶为 x kg ,选择铁路运输时,所需运费为 y 1 元,选择公路运输时,所需运费为 y 2 元,请分别写出 y 1 、 y 2 与 x 之间的关系式。 ( 2 )若公司只支出运费 1500 元,则选用哪种运输方式运送的牛奶多?若公司运...