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Amy 發問於 社會及文化語言 · 1 十年前

中一數學 algebraic equations

我唔識呢幾題,唔該大家幫幫手,教教我!(耍肯定答案正確!!)

我要step,一步一步,先夠清楚

用代數

1. Kelvin and Cherie have the same amount of money. They go to a fast food

restaurant to buy lunch boxes. Kelvin buys six lunch boxes and has $12 left. Cheri

buys four lunch boxes and has $58 left.

a) Find the price of each lunch box.

b) How much does kelvin have originally?

2)Sam pays $110 for 2 boxes of ice cream and 4 bottles of soft drink in a supermarket. If the price of each bottle of soft drink is one-third that of each box of ice cream,find the prices of

a) a box of ice cream,

b) 3 boxes of ice ice cream and 5 bottles of soft drink.

2 個解答

評分
  • Peter
    Lv 7
    1 十年前
    最愛解答

    First one: This is no need to use algebra to solve.

    Cherie brought 2 less lunch boxes than Kelvin and has $46 ($58-$12) more. Thus each lunch box costs $23 ($46/2). So Kelvin and Cherie each has $150 ($23x6+$12) originally.

    Of course if you insist to solve it with algebra, you can do this:

    Let Kelvin and Cherie each has X dollars.

    Let each lunch box costs Y dollars

    equation 1: X=6Y+12 (Kelvin's case)

    equation 2: X=4Y+58 (Cherie's case)

    Then 6Y+12=4Y+58, and Y=23, X=150

    Second one:

    Let each box of ice cream costs X dollars.

    Let each bottle of soft drink costs Y dollars.

    equation 1: 2X+4Y=110 (Sam's purchase in supermarket)

    equation 2: Y=1/3(X) (price of each bottle of soft drink is one-third that of each box of ice cream)

    Then sub equation 2 into equation 1: 2X+4/3(X)=110

    6X+4X=330

    X=33 (price of a box of ice cream)

    Y=11 (price of a bottle of soft drink)

    Price of 3 boxes of ice cream and 5 bottles of soft drink = 3x33+5x11 = 154

  • ?
    Lv 7
    1 十年前

    1.

    K=Kelvin's original money=Cheri's original money.

    L=Lunch Box price.

    K=6*L+12

    K=4*L+58

    6L+12=4L+58

    2L=46

    L=23 (a)

    K=6*23+12=$150 (b)

    2.

    C=Ice-cream price

    D=Softdrink price

    D=1/3*C -> C=3D

    $110=2C+4D

    110=6D+4D

    110=10D

    D=11

    C=$33 (a)

    (b) 3*33+5*11=99+55=$154

    請努力學習,今次諳住良心害你一次。

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