The following table lists the components needed to assemble an end item, A, the amount on hand, and the direct components of each item and, in brackets, the number of each component for each parent.

Item	Amount on Hand	Direct Components
A (end item)	5	B(2), C(1), D(3)
B	10	E(1), F(2), G(1)
C	20	F(2), H(2)
D	15
E	10
F	20
G	5
H	5	J(2)
J	10
K	30
L	10	F(2), M(3)
M	5

a) Draw the product structure tree for the End Item, A.

b) If 60 units of the End Item, A, are to be assembled, how many additional units of B are needed?

calculate the number of Fs required