**Puzzle 168**
So the 2 morphisms are :
$$\alpha_{a',b'}(g \circ h \circ F(f))$$
$$G(g) \circ \alpha_{a,b}(h) \circ f$$
Now check if these two are equal using the fact that \\(\alpha_{a,b}\\) is like taking \\(G\\) and \\(G(F(h)) = h \\) :
$$\alpha_{a',b'}(g \circ h \circ F(f))$$
$$= G(g \circ h \circ F(f))$$
$$= G(g) \circ G(h) \circ f$$
$$= G(g) \circ \alpha_{a,b}(h) \circ f$$