S1-S2 Equations

2012-08-21 9:02 pm

我有3條Equations 唔識,請大家幫幫手!感謝非常!

1.c-5/6+3=2-c/8

2.Ann had $100.She used part of her money to buy 7 ceramic cats,in which 3 of
them are more expensive than the rest by $3.If she had $7 left, how much do the
two types of ceramic cat cost?

3.Ann had a bag of glass beads.She used half of the beads to make a necklace.
She and her sister then use 1/6 and 1/7 of the original number of the beads
respectively to make two bracelets. If there are 16 glass beads left, find the original
number of glass beads.

回答 (1)

PeterChow

2012-08-21 10:58 pm

✔ 最佳答案

1.
c-5/6+3=2-c/8
c+13/6=2-c/8
24c+52=48-3c
27c=-4
c=-4/27
2.
Let $x be the cost of the cheaper cat and $y be the cost of the more expensive cat.
y-x=3---1
100-(7-3)x-3y=7---2
From 1, y=3+x---3
Sub. 3 into 2,
100-21x-9-3x=7
-24x=-84
x=3.5
Sub. x=3.5 into 3, y=3+3.5=6.5
∴The cost of the cheaper cat is $3.5 and the cost of the more expensive cat is $6.5.
3.
Let $x be the original number of glass beads.
x-x/2-x/6-x7=16
4x/21=16
x=84
∴The original number of glass beads is 84.

參考: me

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