C/1 Understand and use proportionality
C/2 Calculate the result of any proportional change using multiplicative methods
- http://www.khanacademy.org/math/arithmetic/rates-and-ratios/e/proportions_1
- http://www.khanacademy.org/math/arithmetic/rates-and-ratios/e/proportions_2
- http://www.khanacademy.org/math/algebra/systems-of-eq-and-ineq/e/graphing_systems_of_equations
- http://www.khanacademy.org/math/algebra/systems-of-eq-and-ineq/e/solutions_to_systems_of_equations
- http://www.khanacademy.org/math/algebra/systems-of-eq-and-ineq/e/systems_of_equations_with_elimination_0.5
- http://www.khanacademy.org/math/algebra/systems-of-eq-and-ineq/e/systems_of_equations_with_elimination
- http://www.khanacademy.org/math/algebra/systems-of-eq-and-ineq/e/systems_of_equations_with_substitution
- http://www.khanacademy.org/math/algebra/solving-linear-equations-and-inequalities/e/inequalities_on_a_number_line
- http://www.khanacademy.org/math/algebra/solving-linear-equations-and-inequalities/e/one_step_inequalities
- http://www.khanacademy.org/math/arithmetic/rates-and-ratios/e/rate_problems_0.5
- http://www.khanacademy.org/math/arithmetic/rates-and-ratios/e/rate_problems_1
- http://www.khanacademy.org/math/arithmetic/rates-and-ratios/e/rate_problems_2