百分数数学题,懂英语和数学的来!there are 900 students in a school ,and 405 of th_英语解答

百分数数学题,懂英语和数学的来!
there are 900 students in a school ,and 405 of them are boys.Also,60% of the students are in junior forms,and 306 of them are girls.
（a）What percentage of the students are girls in the school?
(b)What percentage of the senior students are girls?
(c)How many boys are there in senior forms?
答案我都知道,就是要算式

人气：475 ℃　时间：2019-10-08 11:23:26

解答

（a）（900-405）/900=55%
（b）（900-405-306）/（900*40%）=52.5%
（c)900*40%*（1-52.5%）=171