S$11\mathrm{.}1.($LO S$11\mathrm{.}1)$ Steel mills in three cities produce the following amounts of steel:

Location Weekly Production $($tonnes$)$

A$.$ Richmond $180$

B$.$ Longueuil $260$

C$.$ Hamilton $310$

$750$

These mills supply steel to four cities, where manufacturing plants have the following demand:

Location Weekly Demand $($tonnes$)$

$1.$ Toronto $160$

$2.$ Vancouver $120$

$3.$ Montreal $170$

$4.$ Halifax $220$

$670$

Shipping costs per tonne of steel are as follows:

From To

$1234$

A$.$ $$130$ $$90$ $$140$ $$170$

B$.12011070100$

C$.180130100210$

Because of a truckers$$ strike, shipments are prohibited from Richmond to Toronto. Solve this problem.