<span>(f+g)(x) if f(x)=2/x+1 and g(x)=x-2  
Add f and g together:     (f+g)(x) = (2/x) + 1 + x - 2 = (2/x) + x - 1</span>
        
             
        
        
        
21, 18 1/2, 6.2, 1.75, -1/4, -1/2, -4,-5.9
        
             
        
        
        
I think this is more of an opinion question. What someone could solve mentally may not be the same as someone else's.If it were my worksheet, I'd circle all of them but it may be different for you.
At your level, I'd probably circle:
54 - 10
93 - 20
and 39 - 2
        
             
        
        
        
The numerator could be written a⁴/⁵
The denominator could be written a²/³
Now solve  ( a⁴/⁵) / (a²/³) ==> a⁽⁴/⁵ ⁻²/³)  = a⁽²/¹⁵)
This is the simplest way