C1: Timf cacs booij chung lowns hown 5000 nhuwng nhor hown 1000 cuar cacs soos : 126; 140; 180 

Help me 

xin looix cacs bn vif mays tinhs mik hongr neen khoong vieets ddc daaus

nhuwng: nguoi xong 1 : 5 tik

nguoi xong 2 : 4 tik

nguoi xong 3 : 3 tik

khong ai bi thiet  dau nhe

Trung binh cong tat ca cac so le cos 3 chuwx soos chia het cho 5 bang

trung binhf coongj cacs soos ler nhor hown 2012

timf cacs soos nguyeen x, y sao cho: y/3-1/x=1/3

C2:  timf 2 soos tuwj nhieen a vaf  b b't tichs cuar chungs lak 2940 vaf bcnn cuar chung  lak 210

dichj nhes ( bcnn : booij chung nhor nhaats )

1) tinh cacs gocs cuar △ ABC ,bieets

a) 3A=4B vaf A-B=20ddooj

b) B-C=10ddooj va C-A=10ddooj

viet them chi so 0 vao ben phai phan thap phan cuar cacs so thap phan de cac phan thap phan co chu so bang nhau: 45,82= ; 35, 923=  ?

Tinhs toongr cacs soos hangj cos quy luaatj:

\(\dfrac{1}{2}+\dfrac{11}{6}+\dfrac{35}{12}+\dfrac{79}{20}+....+\dfrac{980099}{9900}\)

Cho tam giac ABC có B=80độ,C=40độ.

a,So sanh cacs canh tam giac ABC

b,Trên tia đối cuar tia CB lay diem D bat ki.So sanh:AD vaf AC