get string after and before word

Programmer Question

i need to get a set of values after certain 14 length of a string and before the last 5 stringss.

eg:

Theboyisgoingt9123holdi: so i need to get the value 9123
iamfullofmeats89holdi: i need to extract value 89

so the algorithm here is, i am trying to extract the values that comes after the 14th length of the string and just before the last 5 characters of the same string.
its always whats between 14th and last 5 characters.

i am coding in vb.net.
any ideas is great appreciated.

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