It gets harder when letters representing by double digits numbers, and the way to decode is to remember

there is no letter starting with 3 to 9 and try to go ahead by meaning any option available. In this case there

is no letter for ‘85’ so it is ‘8’ and ‘5’ which are ‘h’ and ‘e’ so we have ‘he’ then ‘1’ and ‘2’ twice if we put ‘a’ and

‘b’ our word would be ‘heabab’ which is meaningless in English, but if we take ‘12’ as ‘l’  and ‘15’ as ’o’

then we have ‘hello’ which is perfectly sensible.

So this code will be: