Unmanned Aerial vehicles (UAV) or drones have significant market potential due to their high mobility and cost savings. Simultaneously, the hybrid delivery system in which collaborative use of trucks and drones is also receiving much attention and intensively studied as traveling salesmen problem with drone (TSP-D). This delivery system has significant advantages since it can selectively exploit the strength of each vehicle. ​However, in many cases, drones are only used as an assistant method of supporting truck delivery. In this paper, as a reverse idea, we present a new model, named drone routing problem with truck (DRP-T), in the form of a truck assisting drones' delivery. We present a mathematical model formulated as mixed-integer linear programming (MILP) and conduct a comparative analysis with one of the existing TSP-D models with an actual map-based case study. Our experiments show that it is possible to have substantial savings with the proposed model compared to the truck-only and TSP-D model.