David and his children went into a bakery where they sell donuts for
$1.75 each and brownies for $1.25 each. David has $20 to spend and
must buy a minimum of 12 donuts and brownies altogether. Also, he
must buy a maximum of 4 donuts and a maximum of 12 brownies. If
represents the number of donuts purchased and y represents the
number of brownies purchased, write and solve a system of
inequalities graphically and determine one possible solution.