Respuesta :

Our equations are:  

B/S=5/4  

B+S=720  

By substituting the first equation solved for S, S=B*(4/5), into the second equation, we get:  

B+(B*(4/5))=720  

B*(9/5)=720  

B=720*(5/9)  

B=400  

If you wanted to solve for the small number too:  

B+S=720  

(400)+S=720  

S=320