ANSWER
The two lines are perpendicular if 
EXPLANATION
Given two lines:

and

We can tell wether these two lines are perpendicular to each other using their slopes.
If the product of their slopes is -1, the then the two line are perpendicular.
For example:
The line

has slope

and the line

has slope

The product of the two slopes is

This implies that:

Therefore the two lines are perpendicular.
Answer:
the angle of 3 is 50
Step-by-step explanation:
What you would do is add 90 to 40 which would get you 130. Then you will subtract 130 from 180 which gets you 50 for angle 1. Since angle 1 is across from angle 3, angle 3 will also be 50.
Answer:
sorry can't help :)
Step-by-step explanation:
Tax: 52.5 x .08= 4.2
Tip: 52.5 x .20= 10.5
Total: 52.5+ 4.2+ 10.5= $67.10
Answer:
32
Step-by-step explanation:
18+14