/sci/ - Science & Math

Ok /sci/, so I'm a brainlet who is taking my first course in proof-oriented mathematics and this question has me stumped.

Using the axioms in pic I need to prove that |ab| = |a||b|

now on an intuitive level it's super obvious why this is the case, but I don't know where to start to prove it

if anyone could set me on the right track I'd love you forever