Exercise $7\mathrm{.}3,$ Page $415.$ Figure $1$ shows a flow network on which an s$-$t flow has been computed.

The capacity of each edge appears as a label next to the edge, and the numbers in boxes give the amount of flow sent on each edge $($Edges without boxed numbers have no flow being sent on them$).$

$($a$)$ What is the value of this flow? Is this a maximum s$-$t flow in this graph?

$($b$)$ Find a minimum s$-$t cut in the flow network pictured in Figure $1,$ and also say what its capacity is$.$