Solution:
Pick some smart number for x,
let x=2 (I chose x=2 as in this case monthly shipments would be X/2=1).
From January to April, inclusive 4x=8 brooms were produced and
in May the company paid for storage of 8-1 =7 brooms,
in next month for storage of 6 and so on.
So the total storage cost would be:
= 1 ∗ (7+6+5+4+3+2+1+0)
= 28
--> as x=2 , then 28 = 14x
So the answer is 14x