14) C

Total number of sales in the week = 80 + 30 + 100 + 120 + 70 = 400
This may seem tricky but remember, always try and think outside the box.

If we work out the percentage of sales for each day compared to the whole week, we will see that on Wednesday, Terence made 100 sales out of the 400 in total. This is one quarter. None of the sections in the pie chart represent ¼ of the whole pie chart. This means that Terence forgot to draw in Wednesday.