Given: 48 students took the exam.
A total of 18 + 10 = 28 students scored 80% or above.
To find the percentage, take the part (28 students) divided by the whole (48 students) then multiply the quotient by 100.
(28 students / 48 students) x 100 = 58.33%
58.33% of the students who took the exam scored an 80% or higher