The ratio of students that wear glasses to students that do not wear glasses is 1:4. If there were a total of 30 students. How many students wear glasses?

6

Step-by-step explanation:

For every 5 students, 1 wears glasses and 4 don't.  If you take the total number of students, 30, and divide it by 5, you have 6 groups of 5 students.  There will be 1 student for each of those groups wearing glasses, or 6 students.

the answer is 510

step-by-step explanation:

15 • 13 = 195

15 • 12 = 180

15 • 5 = 75

12 • 5 = 60

195 + 180 = 375

375 + 75 = 450

450 + 60 = 510