Unit 3 · Measurement and Data
330c Remaining — Max 20c Coins?
Lesson 12 of 12
About this lesson
Susie pays $10 for a $2.20 purchase and gets $7.80 change. The catch: no $1/$2 coins, no notes, and the change has EXACTLY nine 50c coins. The remaining $3.30 must come from 20c, 10c, and 5c coins. What is the MOST 20c coins she can have? This is a two-step constraint problem — first pin down the remaining amount, then maximise one coin denomination.
Chapters
Question
A pen costs $1.40 and a pencil costs 80 cents.
Susie buys a pen and a pencil and pays with a $10 note.
The shop assistant has no $1 or $2 coins, and no notes.
Susie's change contains exactly nine 50 cent coins.
What is the greatest number of 20 cent coins that Susie could have in her change?
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