A school store sells notebooks, folders, pens and pencils. You can buy five notebooks, five folders and two pencils for $32.00. You can buy two notebooks, two folders and three erasers for $13.50. Find the cost of one eraser if each pencil costs $1.00.
Last week’s answer:
Split the coins into 3 groups (Group A, Group B, Group C) of 3.
- Weigh Group A vs. Group B.
- If equal → heavy coin is in Group C.
- If not equal → heavy coin is in the heavier group of the coins weighed.
- Take the group of 3 that you now know has the heavier coin. Pick two coins from that group and weigh those two coins against each other.
Otherwise → the heavier pan’s coin has the heavier coin.
If equal → the third coin is the heavier coin.