Lepton universality implies that vector bosons are coupled equally to the three families of leptons. This feature is implicit in the standard model which is our current model in particle physics. Lepton universality tests seek to find some anomaly. We are interested in perform a lepton universality test studying the decay B+c → [(ηc → pp ̄) l+ νl]. We have started studying the B+c → [(ηc → pp ̄) μ+ νμ] decay to subsequently measure its branching fraction. We are using data from the LHCb of the run 2 pp collision of the years 2016 and 2017.