The mistake is that there is a greater common factor than 18. It's 36.
36 divides 36 evenly.
36 divides 72 evenly.
45
Sheila's mistake was saying that the GCF of 36 and 72 is 18. The correct answer is 36.
Since 36 is a factor of 72, it is automatically the GCF.
The GCF of 18 and 36 is 18.
The GCF is 18.
The GCF is 18.
The GCF is 18.
It would be 18.
The GCF is 6.
The GCF is 18.
The GCF is 18.
The GCF is 18.
Since 36 is a factor of 72, it is automatically the GCF.