How can I solve this?

Question

A Web music store offers two versions of a popular song. The size of the standard version is 2.2 megabytes (MB). The size of the high-quality version is 4.2 MB. Yesterday, there were 1090 downloads of the song, for a total download size of 2998 MB. How many downloads of the high-quality version were there?

Answer 1

 

Let x = number of standard downloads

Let y = number of high quality downloads

 

x + y = 1090     

2.2x + 4.2y = 2998

 

Solving for x in the first equation,

 

    x + y = 1090

           x = 1090 - y

we can now substitute into the second equation

 

   2.2(1090 - y) + 4.2y = 2998

 

   2398 - 2.2y + 4.2y = 2998

 

   2y = 2998 - 2398

 

   2y = 600

 

   y = 300

 

There were 300 high-quality downloads

 

 

Answer 2

B=# of standard versions

M=# of high-quality versions

2.2B+4.2M=2998

B+M=1090

22B+42M=29,980

B=1090-M

22(1090-M)+42M=29,980

23,980-22M+42M=29,908

23,980+20M=29,980

20M=29,980-23,980

20M=6000

M=6000/20

M=300 downloads of high-quality