Product 6 was launched at the start of November. Therefore, the bar for sales of product 6 are for November and December.
Units sold in November and December = 600
Sales made = (600/100) x 4000 = £24,000
Since cost of 100 units is £4000
Cost of 1 unit must be £40
From the second graph, we can see that sales for product 6 is £6000 in December.
Units sold in November = 6000/40 = 150 units
We know that a total of 600 units were sold in November and December.
Units sold in December = 600-150 = 450 units