This document discusses collaborative task execution between a mobile device and cloud clone to minimize energy consumption on the mobile device while meeting a time deadline. It formulates the problem as a delay-constrained workflow scheduling problem to determine the optimal execution location (mobile device or cloud) for each task. Two algorithms are proposed to solve the problem - a one-climb policy for the special case without execution restrictions, and a Lagrange relaxation-based algorithm for the general case with some tasks requiring mobile or cloud execution. Simulation results show collaborative task execution is more energy efficient than local or remote execution alone.