3/12,7/12,11/12,15/12 arithmetic progression.
jinjing
2016-12-13 15:53:49
( reads)
Common diffrence is 4/12,the next number is 15/12 + 4/12 = 19/12 .
Common diffrence is 4/12,the next number is 15/12 + 4/12 = 19/12 .
breehm
2016-12-16 11:54:44谢谢