Step 1 - Longest carbon chain has 4 carbons. The chain is therefore butane

Step 2 - Number the carbons so that the side chains(methyl ,chloro and bromo groups) are on the lowest numbered carbons.

Step 3 - Identify the side chains as two chloro, one methyl and one bromo.

Step 4 - Writing the name with bromo(alphabetical order) chloro and methyl as the prefixs we get

4-bromo-1,2-dichloro-2methylbutane