 
 <translate> Sum of all the 13 numbers = 13 * 59 = 767
Sum of the first 7 of them = 7 * 57 = 399
Sum of the last 7 of them = 7 * 61 = 427
So, the 8th number = 427 + 399 - 767 = 59.
Thus, the answer is (A). <ibo> Nchịkọta nke nọmba 13 niile = 13 * 59 = 767 Nchịkọta nke asaa mbụ n'ime ha = 7 * 57 = 399 Nchikota nke 7 ikpeazụ n'ime ha = 7 * 61 = 427 Ya mere, nọmba nke asatọ = 427 + 399 - 767 = 59. N'ihi ya, azịza ya bụ (A). 