Okay so there are 100 white balloons, 200 pink balloons, and we are specified that the ratio of pink to yellow is 10:1 soo we can plug 200:20 which can be simplified to 100:10 which can then be simplified to 10:1 there is our ratio. So there are 29 yellow balloons. Therefore there are only 80 balloons left which would mean there are 80 blue balloons!:)