UTG is 42/18/8 in 40 hands. What to do about a HP donk here? Thanks-
SB: 105.86 BB
BB: 78.18 BB
UTG: 150 BB
MP: 68.2 BB
CO: 85.7 BB
Hero (BTN): 188.8 BB
SB posts SB 0.5 BB, BB posts BB 1 BB
Pre Flop: (pot: 1.5 BB) Hero has J

J
UTG raises to 4 BB, MP calls 4 BB,
fold,
Hero raises to 17 BB,
fold,
fold, UTG calls 13 BB,
fold
Flop: (39.5 BB, 2 players) K

6

T
UTG bets 18.76 BB, Hero?