Letters from Answer Key to Percentage?

The answer key is:

D B C B A C B D D B B A B B A D C % this from G2:W2 in an Excel Spreadsheet

While (for example), Student 1's answers are:

A A B C C B A B A B B A B B A B B % this is from G3:W3 in an Excel Spreadsheet

How do I convert the student's answers to a percentage based on their answers vs the answer key?

What I have so far is:

multAns = cell2mat(txt4); % txt4 was the student's answer

ansKey = cell2mat(txt1); % txt1 was the answer key

multipleChoiceScore = scoreMult./ansKey;

Any help would be appreciated. Thank you very much!

Answer 1

[David Hill]

percentCorrect = 100*sum((multAns-ansKey)==0)/length(ansKey);%assumes every question was answered