13:1 is a part:part ratio. Since the students and teachers make up the whole 224 people, the two parts make the whole, so the whole is 13 + 1 = 14. The part:whole ratios are:
- Students 13:14
- Teachers 1:14
Now we can set up a proportion. Let x = the number of students:
13/14 = x/224
Solve for x.