Answer:
Definition of Midpoint
Step-by-step explanation:
Say RS is 20(as an example), that would make RT 10 and TS 10. The two halves of the midpoint are congruent. 
 
        
             
        
        
        
Answer:
4:1 (divide both sides by 3)
Step-by-step explanation:
 
        
             
        
        
        
Answer: Maybe 72 cm? 
Step-by-step explanation: I did 6 times 12 
Sorry if it’s wrong :(