Create an omnifix calculator
Python 3, 159 158 152 144 136 135 132 bytes

def t(i,a=1):
 while'-'&lt;l[i]!='/':i+=1;a=0
 if a:l[i]='(';i=t(t(i+1));l[i-1]=')'
 return-~i
*l,=input()
t(0)
print(eval(''.join(l)))


Try it online!

Doesn't allow negative numbers (though -0-5- works of course) and requires python operators.