Please help me this is due in 2 hours you need to explain your answer plz?

1) one muffin costs $1.50

one quart of milk costs $3.00

2) 10 videos, 30 CDs

Step-by-step explanation:

1)

m = cost of one muffin

q = cost of one quart of milk

System of equations:

3m + 1q = 7.5

8m + 2q = 18

I multiplied the first equation by -2 to eliminate the 'q' values

  -6m - 2q = -15

+ 8m + 2q = 18

    2m = 3

      m = 3/2

find 'q':  

3(3/2) + q = 7.5

9/2 + q = 15/2

q = 6/2 or 3

2)

c = # of CDs sold

v = # of videos sold

System of equations:

c + v = 40

4c + 6v = 180

I solved first equation for 'c' to get c = 40 - v

4(40-v) + 6v = 180

160 - 4v + 6v = 180

2v = 20

v = 10

10 + c = 40

c = 30