You just have to divide in each case the number of chocolates to the corresponding number of emplyer to find out that rate.
Ex:
Workers Bars
10. 35
20. 70
40. 140
80. 280
To fi d out the rate:
35/10 is 3.5
70/20 is 3.5
140/40 is 3.5
280/80 is 3.5
So the last option from your list is the answer: 3.5