Ok, sorry about that muz.
I apologize, so I am going to help out.
Try this out. Take the fraction that you want to make a decimal, ie, 3/4.
Multiply it by a 100, so you get:
300/4
Then just divide 300 by 4, so you get 75. Then divide by 100 since you multiplied by it earlier, and voila, you get .75.
With 2 1/2, think of it first as 2 wholes, so 2, then 1/2, do the same process, and get .5. Add .5 to 2 and you get 2.5.
Those are useful tricks.