ọi tuổi cha là a=> tuổi con gái là 2/5 a=> tuổi con trai là 3/4*2/5a=3/10a
ta có a+2/5a+3/10a = 85
=> 17 /10a= 85
=> a= 50
=> bố 50 tuổi, con gái: 2/5*50= 20 tuổi, con trai: 85-50-20=15 tuổi

k cho mink nhe

AI TRA LOI TRUOC MINH SE cho 1 dung nho co loi giai ,dap so .ko tra loi linh tinh cam on nhieu cac ban giup minh nhe

Dung vay

Hi everybody . My name is Nhu Y, I am 11 years old and I am a student of grade 6B junior high school in Hai Lam. My favorite subject is English. My favorite sport is badminton, .... I usually watch TV in my free time. I go to school from Monday to Saturday. I always do my homework every morning. I love my family . My family has 7 people: three, me, 3 brothers, 1 head and me. My husband is a farmer, my mother too.My first brother is an electrician, his second brother is a mechanic, his third brother is a bricklayer. My sister is a worker. and i am a student, ...

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# MissyGirl #

Dịch là:

Hi everybody . My name is Nhu Y, I am 11 years old and I am a student in grade 6B Hai Lam secondary school. My favorite subject is English. My favorite sport is badminton, .... I usually watch TV in my free time. I go to school Monday through Saturday. I always do my homework every morning. I love my family. My family has 7 people: three, mother, 3 brother, 1 sister and me. My father is a farmer, so is my mother. My first brother is an electrician, his second brother is a chameleon, his third brother is a nephew. My sister is a worker. And I'm a student, ...

Hk tốt

hello everyone. My name is Nhu Y.I'm eleven years old. I'm studying in class 6B at Hai Lam lower secondary school. My favourite subject is English. My favourite sport is badminton. I usually watch TV in my free time. I go to school from Monday to Saturday . I alway do homework in morning. I very love my family. There are seven peoples in my family:my father, my mother, my three brothers, a sister in low and me.My father is a farmers, my mother is a farmers too.My first brother is an electrician, my second brother is a (mình ko hiểu), my third brother is a bricklayer.My sister in low is a worker and me is a student.

        anh trai thứ 2 bạn làm nghề gì vậy ?Nói rõ ra nhé mình ko hiểu được ^-^

Gọi số học sinh giỏi là a, số học sinh khá là b, học sinh cả lớp là c

Ta có: a=1/5.c+3

           b=1/2.c+9

           a+b=c

=>1/5.c+3+1/2.c+9=c

=>7/10.c+12=c

=>c-7/10.c=12

=>3/10.c=12

=>c=12:3/10

=>c=40

Vậy lớp 5b có 40 học sinh

 Số học sinh trung bình chiếm :

  1 - 3/8 - 1/2 = 1/8 ( số học sinh )

Số học sinh của lớp đó :

  4 : 1/8 = 32 ( học sinh )

   đ/s : ...