You are tasked by your teacher to help her in the computation of your grade for preliminary period. the grade will computed based on the following formula.
CRA=summation of all the quizzes, recitation,board works,assignments,and other requirements.

prelim grade= (Cra*2+major exam)*60+40
(total CRA)*2+major exam
the program will return a letter grade based on the given conditions
letter grade score range
a 100
b 90-99
c 80=89
d 75-79
F below 75

it will display the students name, prelim grade and oblained letter grade