Answer
$400$ mLs of the first one, and $600$ mLs of the second one.
Work Step by Step
If he uses $x$ mLs of the first one, he uses $1000-x$ mLs of the second one.
Then our equation is:
$0.05x+(1000-x)0.2=1000\cdot0.14\\0.05x+200-0.2x=140\\0.15x=60\\x=400$
Thus, he used $400$ mLs of the first one, and $1000-400=600$ mLs of the second one.