Vera studies the extinction of the bear population of Siberia over time. The number of bears $t$ years since Vera started tracking it is given by the following function: $B(t)=2190\cdot e^{-0.3 \large t}$ **What is the instantaneous rate of change of the number of bears after $2$ years?** [[☃ radio 1]] **In what units is this rate of change measured?** [[☃ radio 2]]