Answer:
Using the information you sent us, here is a possible solution:
23 = 13
This is because you are changing a base five number to its base
ten equivalent.
We don't know how familiar you are with number bases, but we
normally count in tens  so it is called a base ten system. The
numbers we use are combinations of the numbers 0, 1, 2, 3, 4,
5, 6, 7, 8, 9.
In the base five system, the numbers are 0, 1, 2, 3, 4.
To give you some idea, here are some base ten numbers and their
base five equivalents:
Base 10 

Base 5 
0 

0 
1 

1 
2 

2 
3 

3 
4 

4 
5 

10
(this is one zero, not ten)

6 

11
(this is one one, not eleven)

7 

12 
8 

13 
9 

14 
10 

20 
11 

21 
12 

22 
13 

23 
14 

24 
15 

30 
etc. 


So to change base ten 13 to base five,
you have 2 groups of five and 3 units, which gives you
13(base 10) = 23 (base 5)
