9. Two computer warehouses supply computers to three schools. Warehouse A has 12 units, Warehouse B has 20 units; School $A$ needs 9 units, School $B$ needs 15 units, School $C$ needs 8 units. It is known that the distances from Warehouse A to Schools $A, B, C$ are 10 km, 5 km, 6 km, respectively; the distances from Warehouse B to Schools $A, B, C$ are 4 km, 8 km, 15 km, respectively. If the transportation cost per unit per km is a constant $a$ yuan. Then Warehouse A should supply School $A$ with $\qquad$ units, School $B$ with $\qquad$ units, and School $C$ with $\qquad$ units, to minimize the total transportation cost.
$9.0,4,8$