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### Course: Early math review>Unit 4

Lesson 5: Word problems within 20

# Addition and subtraction word problems: gorillas

Sal solves addition and subtraction word problems.

## Want to join the conversation?

• does this count as clearing a variable? something like pre algebra ?
• I have always had trouble with math and understanding but one question How would set up a problem for a subtracting. I have seen people set it up two ways for an example the one you did for 20- 5 ive seen it both ways and subtracted two ways with burrowing and not borrowing which way is the correct way?
• 20 - 5 does require borrowing. Whenever a number goes under 0, it always has to borrow from it's big brother. 0 - 5 goes under 0, so it has to borrow from it's big brother, the two. 2 - 1 = 1, and now the 0 becomes 10. 10 - 5 = 5 and 10 + 5 = 15! The answer is 15! I hope this helps!