max position of a char in string

Hi,

How do I get max position of a character in a string
for eg.

If the string has the value

('find value of the variable ')

I want to know the position of the char 'e' of the word variable
Basically all characters after this point will be spaces (ascii 32)
till end of string .

select instr('find value of the variable','e',-1) from dual