Word Problems: Add & Subtract Within 20 — Answer Key
Part A: Show Your Work
These problems may need two steps. Use the box to show your work.
1. Ava has 8 beads. She finds 6 more, then gives 3 to her sister. How many beads does Ava have now?
Answer: 11 beads
First Ava adds: 8 + 6 = 14 beads. Then she gives 3 away: 14 - 3 = 11, so Ava has 11 beads now.
2. There are 15 crayons in a box. Ben takes 7 and then puts 4 back. How many crayons are in the box now?
Answer: 12 crayons
Ben takes 7 out: 15 - 7 = 8. Then he puts 4 back: 8 + 4 = 12, so 12 crayons are in the box.
Part B: Solve Without a Work Box
Read each problem and write the answer on the line.
1. Zoe has 13 grapes. Kim has 7 grapes. How many more grapes does Zoe have than Kim?
Answer: 6 grapes
To compare amounts, you subtract: 13 - 7 = 6. Zoe has 6 more grapes than Kim.
2. A bus has 18 seats. If 9 seats are taken, how many seats are empty?
Answer: 9 seats
18 - 9 = 9. Taking 9 filled seats from the 18 total leaves 9 empty seats on the bus.
Part C: Think About It
Write the missing number or word on each line.
1. If 8 + 6 = 14, then 14 - 6 = 8.
Addition and subtraction are opposite operations, so if 8 + 6 = 14, then taking 6 back away leaves 8.
2. To find 'how many more,' you should subtract.
Finding 'how many more' means comparing two numbers to see the difference, and subtraction shows that difference.
3. 17 - 9 = 8
17 - 9 = 8. Counting back 9 from 17, or thinking 9 + 8 = 17, gives the answer 8.
4. If Sara has 5 fewer stickers than Tom, and Tom has 12, Sara has 7.
'Fewer' means less than, so you subtract: 12 - 5 = 7. Sara has 7 stickers.