Below are the Common Core State Standards that most closely relate to the following lesson.
Calculating Simple Interest ~ http://www.econedlink.org/e1008
Grades: 6-8, 9-12
6.EE.A. - Apply and extend previous understandings of arithmetic to algebraic expressions.
6.RP.A. - Understand ratio concepts and use ratio reasoning to solve problems.
7.RP.A. - Analyze proportional relationships and use them to solve real-world and mathematical problems.
MP1 - Make sense of problems and persevere in solving them.
MP4 - Model with mathematics.
MP6 - Attend to precision.