Values $off(x,y)$ are shown $in$ the table below.

Let $Rbe$ the rectangle $3x3\mathrm{.}6,4y5.$ Find the values $of$ Riemann sums which are reasonable over$-$ and under$-$estimates for ${\displaystyle \underset{R}{\overset{\phantom{}}{}}}f(x,y)dA$ with $x=0\mathrm{.}3$ and $y=0\mathrm{.}5.$

over$-$estimate:

under$-$estimate: