the ratio of yellow to red balloons is 2:1 respectively. if there are 7 red balloons, how many yellow balloons are there? 7 red balloons means we have twice as many yellow balloons. So 7 * 2 = 14. Written as a proportion, of yellow to red, we have: 2/1 = y/7 where y is the number of yellow balloons. Run this proportion through our search engine to get y = 14.