# maths,,,,,,,,,,,,,,,,,help.................

3. Bobby saves a fixed amount of money every day.He finds that the price of a model is $70 more than his savings in 5 days or $10 more than his savings in 9 days.How much does he save each day?

4. Donna buys some $2 stamps and some $5 stamps. If she spends $54 altogether and gets 15 stamps,how many $2 stamps does she buy?

Update:

要有設and答,and 未知數,例如:a,f,b......

### 1 Answer

Rating

- 1 decade agoFavorite Answer
3〉Let Bobby save $n every day&the model's price is $x

then

5n=x-70 ---1

﹜

9n=x-10 ---2

from 1

5n=x-70

5n+70=x ---3

from 2

9n=x-10

9n+10=x ---4

(將3=4)

5n+70=9n+10

70-10=9n-5n

60=4n

n=60/4

n=15

∴Bobby save $15 each day.

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