K.OA.A.4

For any number from 1 to 9, find the number that makes 10 when added to the given number, e.g., by using objects or drawings, and record the answer with a drawing or equation.

Solve missing addend problems within 10. Proceed from objects to pictures to word problems to expressions and equations.

Example: There were three wolves. How many would have to join to make ten wolves?

Source: Page 9 of Go Math