Consider the following linear program:

Max $2A+3B$

$s.t.$

$5A+5B400$ Constraint $1$

$-1A+1B10$ Constraint $2$

$1A+3B90$ Constraint $3$

$A,B0$

Figure $2\mathrm{.}22$ shows a graph of the constraint lines.

a$.$ Place a number $,$ or $3$