Xian = 56 stamps + 12 per month : 12m + 56 kai = 80 stamps + 8 per month : 8m + 80
when will they have same number of stamps ? set them equal. m = number of months
12m + 56 = 8m + 80 12m - 8m = 80 - 56 4m = 24 m = 24/4 m = 6.....at 6 months, they will have the same number of stamps. 12m + 56 = 12(6) + 56 = 128 8m + 80 = 8(6) + 80 = 128 They will both have 128 stamps
