Common Core State Standards
CCSS.Math.Content.6.RP Ratios and Proportional Relationships
CCSS.Math.Content.6.RP.A Understand ratio concepts and use ratio reasoning to solve problems.
CCSS.Math.Content.6.RP.A.3 Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations.
CCSS.Math.Content.6.RP.A.3c Find a percent of a quantity as a rate per 100 (e.g., 30% of a quantity means 30/100 times the quantity); solve problems involving finding the whole, given a part and the percent.