A company has three plants A$,$B$,$C and three warehouses X$,$ Y$,$ and Z$.$ Number of units, available at the plants are $60,70$ and $80$ respectively. Demands at X$,$ Y and Z are $50,80$ and $80$ respectively. Unit costs of transportation are as follows:

Y

$8$

$3$

$7$

$8$

$3$

$3$

$9$

$5$

Find the allocation so that total transportation cost is minimum.