Help me please, i don’t get it loll

Can someone me do math because i am having a breakdown rn because i don’t get it

Afrequency table of grades has five classes (a, b, c, d, f) with frequencies of 3, 13, 14, 5, and 3 respectively. using percentages, what are the relative frequencies of the five classes?

What is r i 4.5+10r=-6.5 with work pls