Let's denote the original cost of each puzzle as \( x \).
Since Molly has 6 grandchildren, she will need to buy 6 puzzles. The total cost for the puzzles at the original price would be: \[ 6x \]
However, the puzzles are discounted by $0.50 each, so the cost per puzzle after the discount is: \[ x - 0.50 \]
Therefore, the total cost for the 6 puzzles after the discount becomes: \[ 6(x - 0.50) = 6x - 3 \]
According to the problem, the total amount Molly spent is $27. Thus, we have the following equation: \[ 6x - 3 = 27 \]
Next, we can solve for \( x \):
- Add 3 to both sides: \[ 6x = 27 + 3 \] \[ 6x = 30 \]
- Divide both sides by 6: \[ x = \frac{30}{6} = 5 \]
Thus, the original cost of each puzzle is \( x = 5 \) dollars.