(a)  

(a)  

(a)  

(a)  

(a)  

(a)  

(a)  

(a)  

(a)  

Simplifica  $\frac{15}{9}$  

(a)  

 $\frac{5}{8}+\frac{1}{2}=$  

(a)  

 $\frac{5}{6}-\frac{4}{12}=$  

(a)