1031 Exchange, Where can you put your gains?

[Wesley Hoover]

I am currently reading the Loopholes of Real Estate by Garret Sutton, and a question I have popped up. If I am purchasing property B using the gains I have from selling property A, does all of the gains acquired have to go into the down payment or could they go towards repair costs? For example: If I sold property A for $130,000 and bought it at $100,000, could I break up the $30,000 into property B? Put $20,000 down to purchase then the remaining $10,000 towards a new HVAC or roof?