s1 to s2 Mathematics

2012-08-06 7:36 am

1) In a party, the number of adults is 6 more than 9 time that of children. The total number of people there is 66. Find the number of adults in the party.

2) Mike has 4 times as many stamps as Kevin does. If Mike gives 16 stamps to Kevin, he still has 25 more stamps than Kevin does. How many stamps does each of them have originally?

3) A sum of money is just enough to buy 16 apple. If the price of each apple is reduced by $0.5, 2 more apple can be bought with the same amount of money. How much is the sum of money?

4) Two months ago, the total weight of Leo and Wilson was 130 kg. They went to a fitness centre together for physical training. Now, the weight of Leo drops by 1/4 and the weight of Wilson drops by 2/7. If Leo weighs 5 kg less than Wilson at present, what were their respective weights two months ago?

回答 (1)

jinyao

2012-08-07 6:52 am

✔ 最佳答案

1. let the number of children in the party is y, then
y+9y+6=66
10y=60
y=6
so the number of adults in the party is 66-6=60.

2. let Kevin has y stamps originally, then
(4y-16)-(y+16)=25
3y=57
y=19
so Mike has 19*4=76 stamps originally and Kevin has 19.

3. let the unit price of the apples is $y, then
16y=(y-0.5)*(16+2)
16y=18y-9
2y=9
y=4.5
so the sum of money is $4.5*16=$72.

4. let the weight of Leo was ykg two months ago, then
y(1-1/4)=(130-y)(1-2/7)-5
3/4 y=130*5/7 - 5/7 y -5
21y=2600-20y-140
41y=2460
y=60
so the weight of Leo was 60kg two months ago and the weight of Wilson was 130-60=70kg.

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