Laura will go for a run during her lunch break if the temperature is between $60^\circ\text{F}$ and $80^\circ\text{F}$. The average speed, $S$, in miles per hour, at which Laura runs is dependent on the temperature, $t$, in degrees Fahrenheit $(^{\circ}\text{F})$, at the start of her run and can be modeled by the function $S(t)=6+0.1(80-t)$. The distance, $D$, in miles, that she can run in $30$ minutes given that her average speed is $x$ miles per hour can be modeled by the function $D(x)=0.5x$. ** Find an explicit expression that models the distance that Laura runs in $30$ minutes given that it is $t^\circ{\text{F}}$ outside at the start of her run.** [[☃ expression 1]]