29) C

Let the money refunded be ‘R’

Let total money before refunds = ‘M’

Money after refunds = £12240

M – R = £12240

40% paid £15 and 60% paid £20

Let the number of people who attended the concert = ‘P’

(0.6P x 20) + (0.4P x 15) = £12240

12P + 6P = £12240

18P = 12240

P = 12240/18 = 680 people

If 680 people paid £20 in advance, M = 680 x 20 = £13600

Refund = 13600 – 12240 = £1360

Hence, C is the answer