Step-by-step explanation:

First we have to solve the products, divisions and powers in each term. The terms are separated by + or - signs. In this expression there are two terms.
In the first term there's a product inside a parenthesis. This means that we have to solve that first:

Now we can solve the multiplication in the first term:

Solve the power in the second term:

And do the substraction:

Answer:
1/2(4x5) - 2³ = 2