Solve step by step
Now use the bar model to work backwards from what we know after the transfer.
1
Find Box B before the transfer — undo the +120
Box B (before) = 1060 − 120 = 940
2
Box A had 500 more than Box B before the transfer
Box A (before) = 940 + 500 = 1440
Box A had 1440 buttons at first.
Exam tip
Always start from the "After" value
The question gives you Box B after the transfer (1060). Subtract what was added to find Box B before — then use the original difference to get Box A.
Common mistake
Don't add 120 to Box B
Many P3 students add 120 to 1060 by mistake. Remember: 1060 is already after the transfer. To go backwards, you subtract.
Quick quiz
Check your understanding with 2 short questions.
Question 1 of 2
After 120 buttons were transferred, Box B had 1060 buttons. What did Box B have before the transfer?
Question 2 of 2
Box B had 940 buttons before the transfer. Box A had 500 more than Box B. How many buttons did Box A have at first?
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Lesson complete
Well done!
You've completed the Before-After Model Drawing lesson.
This heuristic appears in almost every P3 exam paper.