Heart excitation: A simple model for the time at it takes for an electrical impulse in the heart to travel through the atrioventricular node of the heart is 375 Ct+1 90 + 100, Xt > 90. Adapted from D. Kaplan et al., Understanding Nonlinear Dynamics (New York: Springer-Verlag, 1995) (A) (7 points) Find the relevant equilibrium and use the stability criterion to determine when it is stable. (B) (3 points) Draw a cobwebbing diagram for some initial conditions , > 90. [Note: You can graph the function by hand or use graphing software to plot the function and then draw the diagram]