Answer:
Zero methylene groups
Step-by-step explanation:
Hi, on one side you have the 2.4-dimethylhexane molecule as shown in the figure.
On the other side, you have the methylene group with the following structure:
=CH2
As can be seen there isn't any methylene group in the 2.4-dimethylhexane
Important: don't confuse the methylene group with the methyl group. Methyl group is -CH3 and there are two of them in this molecule.