Answer:
6 is the correct answer
Step-by-step explanation:
Hope it is helpful...
Let numbers of books be 'b' and numbers of CDs be 'c'
We can set up two equations:
Equation [1] ⇒

Equation [2] ⇒

We are solving for the number of books and the number of CDs bought
When we have two equations in terms of two different variables;

and

, that we need to solve, then this becomes a simultaneous equation problem.
First, rearrange Equation [1] to make either

or

the subject:


Then we substitute

into Equation [2]






Now we know the value of

which is

, substitute this value into

we have

Answer:
Numbers of books = 13
Numbers of CDs = 7
The cost is dependent on the time played because the cost and go up without the time going up
Step-by-step explanation:
10 red 6 blue so 16 altogether.
apologies if I'm wrong