London system against c6 Qa5

hello, I'm Elle. So my opening in white is London system. i've encountered this move. 

d4 c6 Bf4 Qa5 c3 b5. what is black's opening called? i think it's improvised since i can't find any opening with that move. what's the best counter for that?

Black's play is unorthodox...it doesn't have a name. Any time you are faced with that kind of opening play, you should first determine if there is a direct threat. If not, follow opening principles: take control of the center and develop your pieces. In this case there is no immediate threat, so you should continue by playing e4, Nd2, Ngf3, Bd3, 0-0, etc. Get those pieces out and get your K to safety. Then you can start creating threats that Black will have a hard time meeting because he wasted time with the Q move and ...b5.

There aren't separate names for what White and Black play in any game. Every game has one opening name based on what is played by both sides.

For example - 1.d4 d5 2.Bf4 c5 3.e3 cxd4 4.exd4 Nc6 5.c3 Nf6 6.Bd3 - What opening is this? It is NOT a London System. In fact, by Transposition, this is the Caro-Kann Defense (the "Normal" move order would be 1.e4 c6 2.d4 d5 3.exd5 cxd5 4.Bd3 Nc6 5.c3 Nf6 6.Bf4).

Another common mistake that illustrates. I hear people say that after 1.d4 f5 2.c4 Nf6 3.Nc3 e6 that "White is playing the Queen's Gambit and Black is playing the Dutch". Uhm, No! This is simply put a Dutch Defense. White is not playing a Queen's Gambit. His moves may be the same as what his moves are in a Queen's Gambit, but after 1.d4 f5, the move 2.c4 does not offer a pawn, and is therefore not a gambit.

So there is no such thing as "White is playing a London, what is Black playing?" Every chess game is one opening, and you are playing the White side or Black side of said opening, keeping in mind, there are transpositional possibilities where you may not even be playing the opening you think you are playing, like the Caro-Kann example above.

One name for it could be "+0.97 according to leela"