  The first simultaneous test of muon-electron universality using
$B^{+}\rightarrow K^{+}\ell^{+}\ell^{-}$ and $B^{0}\rightarrow
K^{*0}\ell^{+}\ell^{-}$ decays is performed, in two ranges of the dilepton
invariant-mass squared, $q^{2}$. The analysis uses beauty mesons produced in
proton-proton collisions collected with the LHCb detector between 2011 and
2018, corresponding to an integrated luminosity of 9 $\mathrm{fb}^{-1}$. Each
of the four lepton universality measurements reported is either the first in
the given $q^{2}$ interval or supersedes previous LHCb measurements. The
results are compatible with the predictions of the Standard Model.
