Question

两道英文数学题，很简单

我不知道我的理解对不，所以想看看大家的过程和结果和我一样不
1.In a school, of the students are girls. A year later, the number of girls in the school is increased by and the number of boys is increased by . Find the percentage increase in the total number of students.
2.The marked price of a watch is 40% above its cost. If the watch is sold at a discount of 30%, find the percentage gain or loss.

Answer 1

1、在一所学校里，女生占学生总数的(?)。一年后，这所学校的女生的数量增加了(?)，同时男生的数量增加了(?)。请问学生总数的增幅是多少？

题目没有给出数值（上边的?处），无法解答。如果以xyz表示上述缺少的数值，可以确定计算式。

没原来学生总数为a，则女生数量为ax，男生数量为a(1-x)；一年后女生数量为ax(1+y)，男生数量为a(1-x)(1+z)，则一年后总人数为a[x(1+y)+(1-x)(1+z)]，学生总数的增幅为x(1+y)+(1-x)(1+z)，代入数值即可。

2、一款手表的销售价高于其成本40%。如果这款手表在销售时给出30%的折扣，那么是赚了还是亏了？

设手表的成本是x，则销售价是x(1+40%)，出售时有30%的折扣，则成交价是x(1+40%)(1-30%)=98%x，即亏了2%。

Answer 2

第一题没数字没得计
1.In a school,〔 〕of the students are girls. A year later, the number of girls in the school is increased by〔 〕and the number of boys is increased by〔〕 . Find the percentage increase in the total number of students
2. 〔1+40%〕×〔1 - 30%〕＝98%
100% - 98%＝ 2%
Ans：loss, loss 2%