Find the rule and complete the
expression
m+ [?]
7 11
m
8
12
12
16
17
21
1-12
Enter

Subtract m + ? from m:
11-7 = 4
12-8 - 4
16-12 = 4
21-17 - 4
All the differences are identical, so the rule is to add 4 to m.
The expression would be m + 4