Answer:
To calculate the percentage profit on the sale of the painting, we need to first find the difference between the selling price and the cost price. In this case, the selling price is £300 and the cost price is £180, so the difference is £300 - £180 = £120.
We can then divide this difference by the cost price and multiply by 100% to express the profit as a percentage. In this case, the profit is £120 / £180 * 100% = 66.67%.
Since we need to express the profit as a whole number, we can round this value to the nearest whole number, which gives us a profit of 67%. Therefore, Tom made a profit of 67% on the sale of the painting.