Two purchases are shown one below the other, each with its price.
Compare them - what is extra in the second purchase? The difference in price is its price.
Use that to work out what the item in question costs.
Example
For parents
What does this exercise practice?
Comparing prices practices equation thinking without letters - the child compares two purchases, recognizes that the price difference belongs exactly to the extra item, and uses that price in the first purchase.
Common pitfalls
Many children write down the price difference straight away as the answer. But it is the price of the extra item - if a different item is asked for, one more step is needed.
How to practice at home
When shopping, compare two baskets that differ by only one item - how much does that item cost if you know both totals?
Related: Shopping, The Balance Puzzle