Callie asks her fellow sixth-grade students to name their favorite ice cream flavor. She finds that 3 of every 8 students prefer strawberry to vanilla. if there are 160 students, how many prefer strawberry?

This is a proportionality problem and you can write out an equation with an unknown if necessary. Problems like this will pop up on tests like the SAT's. The information given says that every 8 kids I talk to, 3 will prefer strawberry. So if I ask 16 kids, 6 will prefer strawberry, and if I ask 24 kids, 9 will prefer strawberry. This means that no matter how many kids I talk to, the number that prefer strawberry divided by the total numbers of kids will be 3/8. So, we can write out an equation

3/8 = x/160 since there are 160 kids. Solving for x gives the same answers given above.