There are a number of different types of question here, if you really need help with all of them I suggest talking to your teacher.

That said I'll point you in the right direction with some;

3 3/4 divided by 1/9.

What does that actually mean?

A good way of thinking of it is this. You have a peice of wire of length 3 3/4 metres long and you want to find out how many wires of length 1/9 metre you can cut it up into. Hopefully thinking like this you will see that the answer must be greater than 27 (why?)

Like many things in maths it's possible to work out the answer following some simple rules.

3 3/4 is called a mixed number because it contains a whole number (3) and a fraction (3/4). In order to proceed we convert this into an improper fraction (one that has a greater numerator than denominator)

3 whole is the same as 12 quarters or 12/4. So altogether you can count 17 quaters or 17/4.

So the problem is identical to 17/4 divided by 1/9.

Depending on how you've been taught the next step is

Turn the second fraction upside down and multiply. (The reason why this works is complicated and best left at this stage)

So the problem is the same as 17/4 x 9/1

To work out this you times the numerators and the denominators together

(17 x 9) / (4 x 1)

Acceptable answers 153 / 4 or 38 1/4 or 38.25

Notice that 38.25 IS bigger than 27 as predicted!

Alternative method.

At 17/4 divided by 1/9 stage make sure that you are counting the same thing - convert both fractions into a language they both understand (in this case 36ths

17/4 is the same as 153/36

1/9 is the same as 4/36

So how many wires of length 4/36 metres can you cut out of a length 153/36?

Hopefully you can see that the answer to this is just 153/4 as before!

I prefer the second way of thinking but the first way is quicker with practice.

Decimal division is just the same really.

You need to talk to your teacher about directed numbers if you're struggling with -4 + 5 etc.