Owing to the limited computing resources at the MEC server, reasonable strategies of resources pricing and task offloading are necessary to be designed. In this letter, a scenario of multi-users and single MEC server with limited computing resources is studied, where each end-user has a divisible task which could be offloaded portion to the MEC server for execution, both local and offloaded portions of a task cannot be instantiated for execution at the same time, and a stackelberg game based pricing and offloading is investigated. The game is established based on the relationship between the MEC server resources pricing and task offloading quantities, and the existence of the stackelberg equilibrium is proved. Differential evolution algorithm is then used to find the best strategies of the resources pricing for the MEC server and task offloading quantities for end-users. Simulation results show that the investigations can improve the profit of the MEC server and the utility of end-users, which result in the win-win situation.