can I get help on a specific math problem?

Question

At a school pep rally the ratio of students who wore red to yellow is 7 to 3.  There are 300 students at the pep rally and each student wore either red or yellow.  How many students wore yellow

Answer 1

7 X + 3 X = 300

 

10x = 300

 

x = 30

 

7 * 30 = 210 red

3 * 30  = 90 yellow