Answer:
The exact same as subtracting. 
Example 
5 + (-2) = 3
 
        
                    
             
        
        
        
8:15 am is the answer because if u add up all of the timings it will become an hour and a half 
And when u minus an hour and a half from 10:45 u get 8:15
        
             
        
        
        
Q1
Answer:

Step-by-step explanation:

 explanation for second step:
you divide each side by 3 to get rid of the '3' in '3x'
 
        
             
        
        
        
A. The angles at the intersection of the two lines can be proven to be congruent and complementary . so they meet at a right angle and the lines are perpendicular.
<u>Step-by-step explanation:</u>
In above question, In order to find whether AB ⊥ CD, Using compass construction & rounder , keep the tip at A and cut arcs at line CD . Follow the same process again with tip at B and cut arcs at line CD . Do this both sides of Line CD i.e. on left side of AB & on right side of AB. Now, join the intersection points of both side arcs which are intersecting each other. Now, to prove both are right angle to each other i.e.  AB ⊥ CD , can be done by proving congruent  and complementary , so they meet at a right angle and Hence , the lines are perpendicular i.e. AB is inclined to CD at angle of 90°.
 
        
             
        
        
        
I'm pretty sure it's 8.5 > 2.97