There were 90-24 = <<90-24=66>>66 jellybeans in the jar after Samantha snuck some.
There were 66-12 = <<66-12=54>>54 jellybean in the jar after Shelby ate some.
Samantha and Shelby took 24+12 = <<24+12=36>>36 jellybeans from the jar.
Shelby refilled the jar with 36/2 = <<36/2=18>>18 jellybeans.
There are 54+18 = <<54+18=72>>72 jellybeans in the jar.
#### 72