Need help with this question in the image

Answer:
s a
6 3
22 1
30 0
Step-by-step explanation:
Download song .50
Download album = 4
Let s = number of songs
a = number of albums
She can spend 15 dollars
.5s +4a =15
If she downloads 6 songs, let s=6
.5(6) +4a = 15
3+4a = 15
Subtract 3 from each side
3-3+4a = 15-3
4a = 12
Divide by 4
4a/4 =12/4
a=3
She can buy 3 albums
If she downloads 1 album, let a=1
.5(s) +4(1) = 15
.5s +4=15
Subtract 4 from each side
.5s +4-4=15-4
.5s = 11
Divide by .5
.5s/.5 = 11/.5
s = 22
She can download 22 songs
If she downloads 30 songs, let s=30
.5(30) +4a = 15
15+4a= 15
Subtract 15 from each side
15-15 +4a = 15-15
4a=0
a=0