$20 dollars if you start with $18 and subtract what his parents gave him its $10 then double it so $20 is the answer
        
             
        
        
        
Answer:
11.5
Step-by-step explanation:
r= SI×100
 _______
 P×T
 = 9200×100
 _________
 20000×4
= 920000
________
80000
 
        
             
        
        
        
 is the answer.
 is the answer.
This is because the slop is found by the difference of ys over the difference of xs.