You can get the app Air Math I have the app and it helps a lot
Answer:
4/15
Step-by-step explanation:
Answer is C as all other choices are even numbers therefore make the equation non-integer.
Sum means add
the number is x
13 divided by a number is 13/x
the number divided by the number is x/13
so

also can be simplified to

or

translated it is

where x is the number
Answer: No
Step-by-step explanation: Because it is.