From the given mappings, we have
[tex]f(1) = 5, f(4) = 1, f(2) = 7[/tex]
and
[tex]g(3) = 1, g(5) = 4, g(-6) = 2[/tex]
Then the composition of [tex]f[/tex] with [tex]g[/tex], or [tex]f\circ g[/tex], is
[tex]\boxed{f\circ g = \{(3,5), (5,1), (-6, 7)\}}[/tex]
since
[tex]g(3) = 1 \implies (f\circ g)(3) = f(g(3)) = f(1) = 5[/tex]
[tex]g(5) = 4 \implies (f\circ g)(5) = f(4) = 1[/tex]
[tex]g(-6) = 2 \implies (f\circ g)(-6) = f(2) = 7[/tex]
