Answer:
12 meters 
Step-by-step explanation:
Given That :
Length of ladder = 15m
Height of wall =. 9 m
Using Pythagoras rule :
Adjacent² = hypotenus² - opposite² 
Adjacent² = 15² - 9²
Adjacent² = 225 - 81
Adjacent² = 144
Adjacent = sqrt(144)
Adjacent, x = 12
 
        
             
        
        
        
Xt-3=y
Move three to the other side as a positive number 
xt=3+y
Divide everything by x
t=3+y divided by x
        
             
        
        
        
6/15 + 10/15 = 16/15 = 1 1/15
6/15 - 10/15 = -4/15