The following table gives values of a continuous function.

$\backslash$table$[[x,20,25,30,35,40,45,50],[f(x),44,43,33,28,35,44,57]]$

Use the midpoint rule with three subintervals to estimate the average value $f_{\text{a}\text{v}\text{e}}$ of $f$ on $20,50.$

$f_{\text{a}\text{v}\text{e}}=$

$$