What is the answer to this?

5-Ethyl3-Methyloctane

Explanation:

Step in the naming of organic compound

Step 1: Take the longest continous carbon chain as the root hydrocarbon and name it according to the number of carbon atoms it contains, adding appropriate suffix to indicate the principal substituent group

Step 2:  Number the carbon atoms in the root hydrocarbons from the end which give the lowest number to the suffix, and then the prefix

Step 3:  Indicate other substituents by prefixes proceed by numbers to show their positions on the carbon chain

Applying the step above,

The longest carbon chain is  8, and the fuctional group is the single chain (alkane),

5-Ethyl3-Methyl,octane