  In these notes we use the recently found relation between facets of tropical
Grassmannians and generalizations of Feynman diagrams to compute all "biadjoint
amplitudes" for $n=7$ and $k=3$. We also study scattering equations on
$X(3,7)$, the configuration space of seven points on $\mathbb{CP}^2$. We prove
that the number of solutions is $1272$ in a two-step process. In the first step
we obtain $1162$ explicit solutions to high precision using near-soft
kinematics. In the second step we compute the matrix of $360\times 360$
biadjoint amplitudes obtained by using the facets of ${\rm Trop}\, G(3,7)$,
subtract the result from using the $1162$ solutions and compute the rank of the
resulting matrix. The rank turns out to be $110$, which proves that the number
of solutions in addition to the $1162$ explicit ones is exactly $110$.
