Jenna writes 5 fewer facts than Cleo. Let "c" = number of facts Cleo writes.
So an expression we can use to figure out how many facts Jenna writes is:
c - 5
So the table could look something like this:
10 ║ c-5 ║ 5
11 ║ c-5 ║ 6
12 ║ c-5 ║ 7
So if Cleo writes 31 facts, we can still use: c - 5
Plug in c = 31 to get:
31 - 5 = 26 facts for Jenna