f.1 maths - Ans.fyi 參考答案

f.1 maths

[匿名]

2009-10-28 3:03 am

in 代數方程
1. Donna buys some $2 stamps and some $5 stamps.If she spends $54 altogether and gets 15 stamp, now how many $2 stamp does she buy?
2.A cash voucher,either $200 or $300,is given to eash of 45 staff members.If the total amount of thes vouchers given is $11800,find the nuber of staff members who receive a $200 voucher.

回答 (1)

Prof. Physics

2009-10-28 3:11 am

✔ 最佳答案

1. Let x be the numbers of $2 stamp she buys.

So, (15 - x) is the number of $5 stamp she buys

Total value = $54

So, 2x + 5(15 - x) = 54

2x + 75 - 5x = 54

-3x + 75 = 54

-3x = 54 - 75

-3x = -21

x = 7

So, she buys 7 $2 stamp.

2. Let y be the numbers of staff who receive a $200 voucher,

so (45 - y) is the number of staff who receive a $300 voucher

Total value = $11 800

200y + 300(45 - y) = 11 800

2y + 135 - 3y = 118

-y = 118 - 135

-y = -17

y = 17

So, there are 17 staff who receive a $200 voucher.

參考: Physics king

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