Answer:

Step-by-step explanation:
we know that
The circumference of a circle is equal to

In this problem we have

substitute

Remember that
subtends the arc length of the complete circle
so
by proportion
Find the measure of the central angle for an arc length of 

So theres 4 hours and 60min equals 1 hour, so multiply 4 by 60 to get 240, so theres 240 minutes of time on the mp3. So 1/6 of that total time (240min) was on jazz, so what you do is divide 240 by 6 to get 40, so every 1/6 is 40min. So you could say he spend 40min listening to jazz, or you could say he spent 2/3 of an hour listening to jazz
Answer:
Step-by-step explanation:
Part A
Cost = T - (15/100) * T
Cost = (85/100)*T
Part B
You are asked to take 15% off the cost of something. The first equation is very clear how to do that -- just take 15% of T away from T
The second part is not so obvious if you are not familiar with it, but the result will be the same.
Start with the first equation
Cost = T - (15/100) T Change 1 T to 100 / 100
Cost = 100*T/100T - 15/100T
Cost = 85 /100 * T
Part C
Cost = Phone - 14 at Top quality. Red in Graph below
Cost = 75/100 * Phone at Big value. Blue in Graph belos
The graph below is a good way to answer this. I won't solve it algebraically when the graph will give you a much better idea which phone to get.
Answer: Up to a phone cost of 55 dollars, the red phone is the better buy.
After 55$ the blue phone is better.
Try this with a couple of values for phone,