F.1 maths

1)
let the smallest number is y, then the middle would be y+1, the largest would be y+2

because the smallest number is 19/20 of the largest one, so

y = (y+2)*19/20

y = (19y+38)/20

20y = 19y+38

20y-19y = 38

y = 38

so the smallest number is 38, and the middle number is 38+1=39


2)
Let the smaller number is y, then the larger number is y+2

because 2 times the larger one plus 1/4 of the smaller one equals to 49, so

2*(y+2) + 1/4(y) = 49

2y + 4 + y/4 = 49

2y + y/4 = 45

(8y + y)/ 4 = 45

9y = 180

y = 20

so the smaller number is 20, while the larger number is 22

3) let present age be y

y+16 = 2 x 12
y+16 = 24
y = 8

present age is 8 years old

1.let the largest number be y

ans: 19/20y, (19/20y+y)2 ,y

明嗎??

2.有d唔明問題

係咪最大個數 是 最細個數既1/4

若係既話

let the smallest one be y

y+1/4y+1/4y = 49


第二條唔明...因此唔肯定..sor...