A used book store also started selling used CDs and videos. In the first week, the store sold a combination of 40 CDs and videos. They changed $4 per CD and $6 per video and the total sales were $180. Determine the total number of CDs and videos sold.

number of CD's = 30

number of videos = 10

Step-by-step explanation:

The combined number of CD's and Videos sold is 40.

Let the

number of CD sold = a

number of video sold = b

The CD is sold $4 per CD. The videos is sold $6 per video. The combined sales was $180.

Combined number of CD and video

a + b = 40(i)

Cost of the combined number of CD and video

4a + 6b = 180(ii)

a + b = 40(i)

4a + 6b = 180(ii)

a = 40 - b

insert a in equation(ii)

4(40 - b) + 6b = 180

160 - 4b + 6b = 180

160 + 2b = 180

2b = 180 - 160

2b = 20

divide both side by 2

b = 20/2

b = 10

insert b in equation(i)

a + b = 40(i)

a + 10 = 40

a = 40 - 10

a = 30

the correct functions are

h(x) = 3x + 2  

g(x) = 2^x

step-by-step explanation:

i proceed to calculate the different values ​​of k (x)

case 1)  k(x) = g(x) ∘ h(x)

g(x) ∘ h(x)=g(h(x))

k(x) = [2]^[3x + > is the option  4. k(x) = 2^(3x + 2 )

case 2)  k(x) = g(x) + h(x)

k(x) = [2^x]+[3x + 2]=2^x+3x+> is the option  1.) k(x) = 2^x + 3x + 2

case 3)k(x) = h(x) ÷ g(x)

k(x) =  [3x + 2]/[2^x]=3x/(2^x)+2/(2^x)=3x*(2^-x)+2^(1-x)

is the option  3.)   k(x) = (3x)2^(-x) + 2^(-x + 1 )

case 4)k(x) = g(x) - h(x)

k(x) =  [2^x]-[3x + 2]=2^x-3x-> is the option  2.) k(x) = 2^x - 3x - 2 

case 5)  k(x) = g(x) × h(x)

k(x) = [2^x]*[3x + > is the option  5.) k(x) = 2^x(3x + 2)

case 6)k(x) = h(x) ∘ g(x)

h(x) ∘ g(x)=h(g(x))

k(x)=3*[2^x]+> is the option  6. k(x) = 3(2^x) +2