
Christine A. answered 04/24/17
Tutor
4
(12)
Skillful and Understanding Science and Math Tutor
Analyze the sequence. We find that the difference is +2, +4, +6, +8
Do you see the pattern? It is increasing by 2 more each time.
21 + 10 = 31
31 + 12 = 43
43 + 14 = 57