Answer:
a.21,000
Explanation:
The computation of the number of units expected to be sold in the month of  May is shown below:
= Expected sales volume in units in Area X + Â Expected sales volume in units in Area Y + Expected sales volume in units in Area Z
= 6,000 units + 7,000 units + 8,000 units
= 21,000 units
We simply added these three sales volume in unit so that the expected number of unit sold could come