I have a puzzle to solve and have been trying for a while now.

Each letter of the alphabet is valued between 1 - 26.

I have a list of 20 names. (Some have double letters in them such as
Barrett)

Each name has a known value based on the sum of it's letter values. (eg
Barrett MAY be 3+7+2+2+6+10+10 = 40 but I only know the total, NOT the
individual letter values)

Each value of 1 - 26 can only be used once for A - Z.

Requirement - Assign each letter of the alphabet a value between 1 & 26
to give the correct name value. Each letter value is to be used only
once.

Any help would be GREATLY appreciated.