You can reformulate the expression in a more easier way, by using the concept of fraction. And so you get :
[tex]\frac{55}{11(\frac{120}{2*(4+(10+5-7)} )} =\frac{55}{11(\frac{120}{2*(12)} )}=\frac{55}{11(\frac{120}{24} )}=\frac{55}{11*5} = \frac{55}{55} =1[/tex]
