1. a. Derive the diffusion equation for a chemical pollutant by considering the total amount of the chemical between x = a and x = b. b. If u(x, t) is the solution of the heat equation in a rod (0 < x < L), give an expression for the total thermal energy contained in the rod.

please solve d,e,f, and g would be much appreciated thanks

Mr. O'Dell and Mr. Johnson begin running laps around a one mile track at the same time. Mr. O'Dell completes a mile every 6 minutes and Mr. Johnson completes a mile every 8 minutes. How long will it take for them both to finish a lap at the same time?

Please help solve