某校四五六三个年级的学生为玉树灾区共捐款5000元,六年级和五年级捐款数的比是5比3,

算法是600除以（3+4+5）算出来的数再乘以3成4成5就算出没个年级各的多少本书，4年级150本，5年级200本，六年级250本。望采纳！谢谢

我也担要等一下

21 31 41

四年级 2/9
五年级1/3
六年级4/9

（720-20）÷（3+2+2）
=700÷7
=100（人）
100×2=200（人）
100×3=300（人）
200+20=220（人）
答：四、五、六年级各有220人、200人、300人.

40.80.60

I want to be an actor
I want to be an actor,beacuse it is very interesting!
I can sing and dance,play the piano ,the guitar!
I like to work with other young people.
Actor is a good job so I like actor very much!
If I to be a actor.Please call me at 5555555
My Family
Hello!My name is Lucy.I am a student.My father is a doctor ,but he thinks his job is boring.I think study is happy!My mother is a reporter,sometimes she is very busy,but sometimes she is very tired.
My father wants to be a poliseman,because he thinks it is very exciting.My mother wants to be a teacher,because she is very like children!
My father is hand-some（英俊）man and my mother is beautiful woman.I like them very much!
I have a happy family!
额 以上是我原来帮别人写的 现在又写了2篇,看谁合适你就选谁把
My School Day
Hello!My name is Gina.I go to school is five days a week.I usually get up at 5:00.I go to schol at 7:00.To get to school,I take the 7 bus to school.At 8:00,I have math ,its difficult,but I think its very exciting!At 8:50,I have music ,its very relaxing.My favorite subject is history.I like history very much!
School is over at 15:00.After school,I go home.I have dinner at 16:00.Then I do my homework.
I usually take a shower at 20:30.I go to bed at 21:00
My Day
I had a very busy day.First of all I overslpet and by the time I got up,my brother had already taken a shower,So I had a quick shower.And then I ate breakfast.However,by the time I went to the bus station,the bus had already left.So I had to run to school.AND by the time I arrived at my classroon,the ring had already rang.So I realized I was Late.
Don"t you think it is a busy day

我也担要等一下

1＋10％= 1.1
1.1×（1-10％）=0.99
四年级：618÷（1+1.1+0.99）=200
六年级：200×0.99=198
五年级：618-200-198=220
望采纳.

四年级15、五年级45、六年级60
设三个年级借到图书分别为x 3x 4x本
由题有 3x-x=30
得x=15
3x=45
4x=60

21 31 41

1-20%=80% 80%*5/9=4/9 然后用六年级的棵数除以4/9就完成了

设五年级有x人,四年有（X÷11/10）人,六年有(1-1/10)X人
（X÷11/10）+x+(1-1/10)X=618
得到x=220 则 四年有220÷11/10=200人 六年有(1-1/10)×200=198人

四年级210,五年级350,六年级560

一共=60÷（6-4）×（4+5+6）=450本

你好,很高兴为你服务.
1、3+4+5=12
412=3分之1
2、六年级分得12分之5,四年级分得12分之3,12分之5-12分之3得6分之1
如有帮助,望采纳!

设三个年级共有x人,则五年级共有25%x,则四年级共有25%x+40,则六年级公有3/4*(25%x40)=3/16x+30,得方程 25%x+25%x+40+3/16x+30=x解得x=224.答:三个年级共有224人

150
设四年级a人五年级b人六年级c人,有
1、b=0.2(a+b+c)
2/ c=0.6a
3/a-b=45
联立可解得a=75 b=30 c=45

设四五六年级共有x人,则五年级有 20%x 人,四年级有 20%x +45 ,六年级有 (3/5)(20%x +45 ) 人.
由题意得：
20%x +45+20%x +(3/5)(20%x +45 )=x
可解得 x=150