tuổi mẹ hiện nay là

28 : (3-1) x 3 - 5 = 37 tuổi

tuổi con hiện nay là

37 - 28 = 9 tuổi

con hiện nay 9 tuổi                                                                                                                                                                                                mẹ hiện nay 37 tuổi  ủng hộ mk nha

6889 , ủng hộ mk nha

từ 1 - 9 : 9cs

từ 10 - 99 : 

từ 100 - 999 :

từ 1000 - 1999 : 

360 , ủng hộ mk nha

bai toan này ? kho

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20 người 

k mình nha!

Đổi 75%=3/4.Vậy số cam bằng 3/4 số bưởi.
Tổng số cây bằng số phần cây bưởi là: 3/4+3/4+1=5/2
Số cây bưởi là:30:5/2=12(cây)
Số cây cam=số cây chanh=3/4 số cây bưởi là: 3/4*12=9(cây)

có ? cây mỗi loại

500/100*100/10=5*10=50

500/100.100/10=5.10=50   nhớ tk mình nha

 math error

Đặt A=1*2+2*3+3*4+...........+99*100

3A=1*2*3+2*3*(4-1)+3*4*(5-2)+............+99*100*(101-98)

3A=1*2*3+2*3*4-1*2*3+3*4*5-2*3*4+................+99*100*101-98*99*100

3A=99*100*101

A=99*100*101:3

A=333300