P(4p-3q)-pq p=1/2 q=1/4? i dont understand

i got a math test 2morrow and today we had a test practice and i got this problem wrong(the problem is in the title) and i cant seem to understand how to get the right answer and i dont know where to start, and the teacher says that there will be problems on the test that will be similar to these but with different numbers so please give me step by step writing and the answer so that i may see how to get the answer.

It's really easy all you have to is replace the "p" and "q" with the numbers that are given to you.
Here's what it should look like:
1/2(4x1/2-3x1/4)-1/2x1/4 The p=1/2 and q=1/4 are instructions of replacing the letters into numbers.

The next step is solving the problem:
First you start with the parenthesis() (4x1/2-3x1/4) There are two ways solving this, you can cross multiply like this 4/1 x 1/2 = 8/2 x 1/2 = 8/2 =4 or just get rid of fractions by dividing them out.
Like this: 0.5(4x0.5-3x0.25)-0.5x0.25

Start with (4x0.5-3x0.25) first Mulitply 4x0.5 and 3x0.25. After that bring over your subtract sign - Your answer should be like this:2-0.75
Solve again by 2-0.75 and your answer is 1.25

Set up your problem like this:
0.5(1.25)-0.5x0.25

Start with 0.5(1.25)
You are going to Mulitply like so 0.5 x 1.25
and Your answer is 0.625

Do the same thing with -0.5x0.25
Your answer is -1.125

Rewrite the problem like so:
0.625 - 1.125
Your final answer is -0.5
That's one way but the second one is how to solve with fractions like this:
1/2(4x1/2-3x1/4)-1/2x1/4

First you start with the parenthesis() (4x1/2-3x1/4)

1. By first putting a one under four 4/1 then times with 1/2. Like this 4/1 x 1/2

2. Next take the two from 1/2 and put a small two next to 4 and 1 like this: 2x4 and 2x1
Then take 1 from 4/1 and put a small one next to 1 and 2 like this 1x1 and 2x1
You are going to multiply those numbers and you should get: