Question

Isaac downloaded 7 ringtones. Each polyphonic ringtone costs $3.25, and each standard ringtone costs $1.50. If he spends a total of $21 on ringtones, find the number of polyphonic and standard ringtones he downloaded.

Answer 1

6 polyphonic, 1 standard

Explanation:

Answer 2

`6\ polyphonic\ ringtones` and
`1\ standard\ ringtone`

Explanation:

Let

x -----> the number of polyphonic ringtones

y ----> the number of standard ringtones

we know that

`x+y=7`

`x=7-y` -----> equation A

`3.25x+1.50y=21` -----> equation B

Solve the system of equations by substitution

Substitute equation A in equation B and solve for y

`3.25(7-y)+1.50y=21`

`22.75-3.25y+1.50y=21`

`3.25y-1.50y=22.75-21`

`1.75y=1.75`

`y=1\ standard\ ringtones`

Find the value of x

`x=7-1=6\ polyphonic\ ringtones`