8: Advanced Proportional - Addition and Subtraction

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Marty started with a whole box of chocolates and he ate five ninths of the chocolates. That left only 16 chocolates. How many chocolates were in the box at the start?

Student: There are four ninths left. If four ninths is 16 then one ninth is 4. Nine ninths is the whole box. Four times nine is 36.

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Students at the Advanced Proportional stage are learning to select from a repertoire of part-whole strategies to solve and estimate the answers to problems involving fractions, proportions, and ratios. These strategies are based on finding common factors and include strategies for the multiplication of decimals and the calculation of percentages.