Answer: 34 stuffed animals & 17 mystery boxes.
First off, split 51 into three parts, trying to find how much 1/3 is of 51. It equals 17.
The stuffed animals in the machine are “twice as much” of the mystery boxes, so you need to multiply 17 x 2 to find the amount of stuffed animals.
17 x 2 = 34
As for the mystery boxes, you need to multiply it by one.
17 x 1 = 17.
In summary, the answer is 34 stuffed animals and 17 mystery boxes.