Firstly, we calculate how much Julie spent on her initial stock by multiplying the cost of each box, which is £2.40, by the number of boxes, which is 42. This gives us the total cost of the boxes, which is £100.8.
Next, we determine how much money she made in her first round of sales. Julie sold 34 boxes at £3.60 each. To calculate Julie's revenue from the first round of sales, we multiply the number of boxes sold by the price for which she sold each box. The total revenue from the first round of sales is £122.4.
To find the number of boxes Julie had left, we subtract the 34 boxes she'd sold from her initial stock of 42 boxes. There were 8 boxes left unsold.
We then calculate how many individual candles Julie had left. Knowing that there were 18 candles in each box, Julie had a total of 8 boxes * 18 candles = 144 candles left.
Then we find out the number of individual candles Julie sold that day. At the end of the day, Julie had 12 candles left, meaning she must have sold 144 candles - 12 candles = 132 candles individually.
To calculate the revenue Julie got from selling the individual candles, we multiply the total number of individual candles sold by the price for each candle. The total revenue from the individual candle sales is 132 candles * £0.35 = £46.2.
We sum up the revenue Julie got from the box sales and the revenue she got from the individual candle sales to find the total revenue. Julie's total revenue for that Saturday is £122.4 (from box sales) + £46.2 (from individual candle sales) = £168.6.
Finally, we calculate Julie's profit by deducting the total cost of her initial stock from the total revenue she received. In this case, her profit is £168.6 (total revenue) - £100.8 (total cost) = £67.8. So Julie made a profit of £67.8 that day.