Starbucks did a survey and discovers that 6 out of 10 people surveyed prefer mocha flavor coffee over french vanilla. If they have 12,450 customers how many prefer french vanilla coffee?

If 6 out of 10 prefer mocha, then 4 out of 10 prefer vanilla. Since there are 12450 people surveyed, there are 1245 groups of 10 people. (divide by 10)

each one of those 1245 groups of 10 people has 4 people that prefer vanilla, so we multiply 4 by 1245 to get

4,980 customers