Form 1數學問題！急～

1.Let y be the no. of sticker in the smaller group.
Then the no. of sticker in the bigger group is(60-y)
7y=3(60-y)
7y=180-3y
7y+3y=180
10y=180
y=18
Ans:The no. of stickers in the smaller group is 18.




2.Let y km/h be his walking speed.
Then his running speed is 2y km/h.
2(2y)+3y=21
4y+3y=21
7y=21
y=3
Ans:His walking speed is 3 km/h.



3.Let y be the no. of $1-coins of Shirley has.
Then the no. of $2-coins and $5-coins are[2(y+3)+8] and(y+3) respectively.
y+(y+3)+[2(y+3)+8]=97
y+y+3+[2y+6+8]=97
y+y+3+2y+6+8=97
4y+17=97
4y=80
y=20
Ans:The no. of $1-coins,$2-coins and $3-coins are 20,54 and 23 respectively.
The value of $1-coins:
20x1
=$20
The value of $2-coins:
54x2
=$108
The value of $5-coins:
23x5
=$115
The total value of the coins:
20+108+115
=$243

let x be the number of stickers in the smaller group
3x=6(60-x)
3x=360-6x
9x=360
x=40

let x be his walking speed
21-3x=2(2Xx)
21-3x=4x
21=7x
x=3

let she has x $1 coins
than she has x+3 $5 coins
and 2(x+3)+5 $2 coins
x+x+3+2(x+3)+5=97
2x+3+2x+6=97
4x+9=97
4x=88
x=22
so she has22 $1 coins,25 $5 coins,55 $2 coins
she has 22+125+110=$157