How to solve these questions?

Very Simple,

 1st step check butter and 19 is arranged

2nd Check cookies and 23 is taken,

3rd step check final step salt and 92 arranged.

for the new input, Alphabetic order ABCD, which is last i guess its R (Rich)

Number order which is highest 97, so just arranged in this order u will get it. Can solve these question in a minute time