Understand π + π as the number located a distance |π| from π, in the positive or negative direction depending on whether π is positive or negative. Show that a number and its opposite have a sum of 0 (are additive inverses). Interpret sums of rational numbers by describing real-world contexts.

The Number System

- Apply and extend previous understandings of operations with fractions to add, subtract, multiply and divide rational numbers.
Apply and extend previous understandings of addition and subtraction to add and subtract rational numbers; represent addition and subtraction on a horizontal or vertical number line diagram.