Question

Courtney has a total of 88 stamps worth $15.56. Some are 25 cent stamps and some 2 cent stamps. How many of each does she have

Answer 1

Answer: She has 68 25-cents stamps and 28 2-cents stamps.

Explanation:

Let x be the number of 25 cents stamps and y be the number of 2 cents stamps.

Then According to the question , we have

`x+y=88.............(1)\\\\25x+2y=1556...................(2)`

From (1), we have

`y=88-x ...........(3)`

Put value of y in (2), we get

`25x+2(88-x)=1556\\\\\Rightarrow\ 25x+176-2x=1556\\\\\Rightarrow\ 23x=1556-176\\\\\Rightarrow\ 23x= 1380\\\\\Rightarrow\ x=(1380)/(23)=60`

From (3), we have

`y=88-60=28`

Hence, she has 60 25 cent stamps and 28 2 cents stamps.

Answer 2

88 stamps -------------------- > $15.56
A------------------------------>number of stamps ------------ >25 cent
B----------------------------- > number of stamps ------------ >2 cent

A+B=88------------------ > A=88-B
0.25A+.02B=15.56
resolving
0.25(88-B)+0.02B=15.56
22-0.25B+0.02B=15.56
-0.23B=-6.44----------------------- > B=28 stamps of 2 cent
A=88-B-- >88-28=60------------- > A=60 stamps of 25 cent