A tape diagram. 80 percent out of 100 percent of students had an A or B. 20 students out of question mark students had an A or B. StartFraction part Over whole EndFraction = StartFraction 80 Over 100 EndFraction = StartFraction 20 Over question mark EndFraction 80% of the students in Lea’s class earned an A or a B on the weekly math test. If 20 students got an A or a B, how many students are in Lea’s class? 20 is 80% of what number? 20 × 4 = 80, so 100 × 4 = 400 students 20 60 = 80, so 100 60 = 160 students 80 ÷ 4 = 20, so 100 ÷ 4 = 25 students 80 – 60 = 20, so 100 – 60 = 40 students.