We investigate a fairness-aware adaptive resource allocation scheme for the downlink of multihop OFDMA systems. Assuming that the base station has all the channel information, we formulate an optimization problem for an adaptive subehannel-, path- and power-allocation scheme that maximizes system capacity while guaranteeing minimum resources for each user. Since the optimization should be performed in real time, we propose an efficient heuristic algorithm composed of subchannel-allocation, load-balancing and power-distribution steps. The proposed algorithm is simple in that the iterative computations are removed, and accurate in that it performs similarly to the optimum solution.