What is 4 7/8 written as a decimal

Well, the whole number will be on the left of the decimal. 
SO for starters you can simply put 4. ???
Now, what you do next is very easy!
All ya have to do is divide top into bottom.
Like this:
7 divided by 8= .875

Now, just combine 4.??? and the .875 you just got, and theres your answer of:

4.875

~Hope this helped :)