PQ is parallel to NM. What equation can you use to find the length of QM in triangle MNO with line segment PG parallel to NM; PO is 12 units long, PN is 4 units long, and QM is 3 units long?
a. QM = PO - PN
b. QM = (PN / PO) * QM
c. QM = PO + PN
d. QM = (PO / PN) * QM