In complex calculations like this, the precedence goes like this
B = Brackets
O = Of (or Exponent)
D = Division
M = Multiplication
A = Addition
S = Substraction
So, in your formula, it will go like this
1/2x3+1/4x2
= 0.5 x 3 + 0.25 x 2
= 1.5 + 0.5
= 2
Hope this helps.