Usually, no sign before the bracket means juxtaposition.

So 2(1+2) is really (2+4)

Compare 2/2x and 2/2*x where x is (1+2)

The first is 2/(2+4)=1/3, the second is (2/2)*(1+2)=3

Also, there’s no real rule about solving left to right due to associative and commutative properties: 123 = 1*(23) = (12)3 = 312 = 21*3 = 6