有木有英语和数学好的,顺便说下为什么这么做,If25%ofxequals35%ofx,whatis45%ofAgroupchartersthreeidenticalbusesandoccupies4/5oftheseats.After1/4ofthepassengersleave,theremainingpassengersuseonlytwooft

Question

有木有英语和数学好的,
顺便说下为什么这么做,
If 25% of x equals 35% of x,what is 45% of
A group charters three identical buses and occupies 4/5 of the seats.After 1/4 of the passengers leave,the remaining passengers use only two of the buses.What fraction of the seats on the two buses are now occupied?
The road from Jack's house to Jill's is exactly 10 kilometers.At different times,Jack and Jill each left home and walked toward the other's house.They walked at the same rate and they met at noon,4 kilometers from Jill's house.If Jack left at 10:00,at what time did Jill leave?
If a and b are the lengths of the legwork a right triangle whose hypotenuse is 10 and whose area is 20,what is the value of (a+b)^2?

Answer 1

(1)x的25%等于x的35%,那么x的45%等于多少?

x*25%=x*35%
则x=0,所以x*45%=0

（2）一组乘客乘坐三两相同的巴士,并坐了4/5 的席位,现在有1/4的乘客离开,而剩下的乘客只占据了两辆巴士,那这两辆巴士有多少席位有人乘坐?
设每辆巴士的席位数为X,原来你的乘客人数为Y,则有题意得：3X*4/5=Y,所以Y/X=12/5,而题中所求为剩下的乘客3/4Y与两辆巴士总席位2X的比值：（3/4Y）/（2X）=9/10

(3)JACK与JILL的家相距10公里,不同的时刻他们两人分别从自家出发,相对方家的方向走,他们的速度相同,并在12点见面,见面时离JILL的家有四公里远,如果JACK是在10点出发,那么JILL是几点从家出发的?
在离JILL家四公里处相遇,那么JACK所走路程为6公里,走了两小时,那么速度为3公里每小时,因为JILL的速度与JACK相同,那么他走了4/3小时,即小时20分钟,所以他出门的时间为10点40

（4）a和b是直角三角形的两条直边的长度,斜边长度为10,面积为20,求(a+b)^2的值.
面积=a*b=20,因为是直角三角形,所以a^2+b^2=10^2,而(a+b)^2=a^2+b^2+2ab,因此
(a+b)^2=100+2*20=140