On 1−1−2015 balance in capital account of partner was Rs. 1,00,000. He introduced certain amount on 1−5−2015. As per partnership deed interest on capital is to be provided @ 12% p.a. If Profit & Loss Appropriation A/c is debited for Rs. 18,000 as interest on capital, how much amount was introduced by the partner on 1−5−2015?