Program that outputs letter grade based on percentage?

How do I create a script that has a program that takes in a student's score from an Excel Spreadsheet (in percent, i.e. 88%), and translate's (output) it to a letter grade? For example, if a student scores 90% on a test, then that is considered a A- since an A- is 90%-93%, and if a student scores 80%, then that is considered a B- since a B- is 77%-80%. In addition, the percentage at the boundary of each grade is assigned a high grade; for example, if a student’s grade percentage is 90%, the student receives ‘A-’, not ‘B+’ (A- is 90%-93% while B- is 87%-90%). The percent the student scored will be read from an Excel Spreadsheet (I don't know if that'll make a difference in the building of the code). Any help would be appreciated, thank you!

Answer 1

[Walter Roberson]

if this_score >= 90 & this_score <= 93
    this_grade = 'A-';
elseif this_score >= 77 & this_score <= 80
    this_grade = 'B-';
else
    this_grade = 'F';
end