Are you thinking of folding to this raise? Of course not! So let's prepare for the worst case scenerio against a weaker hand:
His hand is 67. = 10 outs. = 20% to win. So, let's raise more than 20% of his potential profit.
Pot is $28.50 @ the time of his raise.Villain has $60 behind. His potential profit = $28+60 = $88. 20% of this is $18. So raise AT LEAST another $18.... say to $35.
If villain has a better hand than our top two pair, we have 9% to win and say nh. If villain puts anymore $ into the pot, he's fucking up and putting you through college.