Divide through everything by <em>b</em> :

Since <em>a/b</em> < <em>c/d</em>, it follows that

Multiply through everything on the right side by <em>b/d</em> to get

and so (<em>a</em> + <em>c</em>)/(<em>b</em> + <em>d</em>) < <em>c/d</em>.
For the other side, you can do something similar and divide through everything by <em>d</em> :

and <em>a/b</em> < <em>c/d</em> tells us that

Then

and so (<em>a</em> + <em>c</em>)/(<em>b</em> + <em>d</em>) > <em>a/b</em>.
Then together we get the desired inequality.
Answer:
57.5 degrees
Step-by-step explanation:
Assuming this is a triangle
a is adjacent is ∠B
b is opposite of ∠B
Use the inverse tangent equation: 
This equals to 57.52880771
You will pay $2.78 per mile for a total of 7 miles you will pay $19.50, but you must remember the taxi driver charges a $2.00 fixed rate so your final total will be $21.50
The amount for the discount is 150$