求式呀! 唔該!

crystalwesley

There are a total of 30$50-cent coins and $2-coins in a moneybox, and the total value of the coins is $42. How many coins of each denomination are there in the moneybox? (use linear equations )

布甸仔媽媽

原文章由 crystalwesley 於 08-3-18 11:44 發表
There are a total of 30$50-cent coins and $2-coins in a moneybox, and the total value of the coins is $42. How many coins of each denomination are there in the moneybox? (use linear equations ):questi ...

Let X be the quantity of $50cents coins, and Y be the quanity of $2 coins

X + Y = 30

0.5X + 2Y = 42

you need to try to solve the equation by yourself, otherwise you cannot improve your mathematics

2bzmummy

長老 ，

原文章由 布甸仔媽媽 於 08-3-18 11:54 發表


Let X be the quantity of $50cents coins, and Y be the quanity of $2 coins

X + Y = 30

0.5X + 2Y = 42

you need to try to solve the equation by yourself, otherwise you cannot improve your mathematic ...

正46

長老真係寶刀未老!

原文章由 布甸仔媽媽 於 08-3-18 11:54 發表


Let X be the quantity of $50cents coins, and Y be the quanity of $2 coins

X + Y = 30

0.5X + 2Y = 42

you need to try to solve the equation by yourself, otherwise you cannot improve your mathematic ...

alicetong

長老 勁

原文章由 布甸仔媽媽 於 08-3-18 11:54 發表


Let X be the quantity of $50cents coins, and Y be the quanity of $2 coins

X + Y = 30

0.5X + 2Y = 42

you need to try to solve the equation by yourself, otherwise you cannot improve your mathematic ...

sorlo

長老真係精靈

vivi_vivi

46,

長老的老不可與你的"老"同日而語喎:;pppp: :;pppp:

原文章由 正46 於 08-3-18 14:24 發表
長老真係寶刀未老!

fungsir

Let X be the quantity of $50cents coins,
then the quanity of $2 coins will be 30-X.


0.5X + 2(30-X) = 42
0.5X + 60 - 2X = 42
   60 - 1.5X        = 42
   60 - 42           = 1.5X

then  X = 12  (the quantity of $50cents coins)

the quanity of $2 coins will be 30-X = 30 - 12 = 18...


This maybe F.1 or F.2 question

can use either 1 or 2 unknown equation

crystalwesley

多謝你們的回應呀!  這是中一的數呀! thanks a lot!!!!

Asian

goodgood ar~