The answer is 72.
You can figure this out using the Pythagorean theorem: C (78) squared - A (30) squared = B squared though since you already know the longest side. 
78 x 78 = 6084
30 x 30 = 900
6084-900= 5184
The square root of 5184 is 72.
        
             
        
        
        
1.00 no problem, I tired thank you
        
                    
             
        
        
        
10+8h=66
minus 10 both sides
8h=56
divide both sides by 8
h=7
worked 7 hours
        
                    
             
        
        
        
The common ratio of sequential values is 
   18.2/26 = 0.7
The missing value is
   12.74*0.7 = 8.918
The appropriate choice is ...
   d.  8.918