36.64-21=15.64
15.64-6.14=9.5
The answer is she made $9.50 worth in local calls last month
D=z, j=4d,
If w=j, then w=4d,
If w=4d and d=z then:
w=4z
Circumference = 360 degrees
<span>Circumference = 2π radians (comes from 2*pi*radius) </span>
<span>Therefore </span>
<span>360 deg. = 2*π radians </span>
<span>180 deg. = π radians </span>
<span>1 deg. = (π/180) radians </span>
<span>75 deg. = 75(π/180) radians </span>
<span>75 deg. = 75π / 180 radians </span>
<span>don't bother to try and simplify π (it is an irrational number) </span>
<span>however you can simplify 75/180 </span>
<span>both are divisible by 5 </span>
<span>75π/180 = 15π/36 </span>
<span>both are divisible by 3 </span>
<span>75 deg. = 5π/12 radians </span>
<span>We normally don't bother to go further, unless you actually need it as a decimal fraction (in which case, you will have an approximation) </span>
<span>75 deg. ≈ 1.308997 radians</span>
Given:
Cost of 1 digital song = $1.05
Cost of 2 digital song = $2.10
Cost of 5 digital song = $5.25
To find:
The equation and the cost of 25 downloaded digital songs.
Solution:
Let us take two points (1, 1.05) and (2, 2.10).
Here 
Slope:
m = 1.05
Using point-slope formula:
Add 1.05 on both sides, we get
Here x is the independent variable and c is the dependent variable.
So that substitute x = n and y = c.
The equation is c = 1.05 n.
Substitute n = 25 in the equation.
The cost of 25 songs is $26.25.
