Since you're looking for students who scored at least 81, then you're looking at the last two rows on the table, because 81-90 and 91-100 are all at least 81. Add those number of students together, 20 + 7 = 27
Now, add up all the students in the table, which should equal 50. Since 27 out of 50 students made at least an 81, divide the numbers.
[tex]\frac{27}{50} = 0.54[/tex]
Move the decimal to the right two times, and your answer will be 54%
