Answer
The major product will be 2-bromo-1-phenylpropane. The reaction is free-radical addition of HBr.
Work Step by Step
The group shown in a box in the picture is written as R.
The following are the steps:
1) Initiation- radicals are formed. So the two radicals formed would be R-O and O-R.
2) The hydrogen attaches to one of the radicals to form a R-O-H and a Bromine radical.
3) That bromine radical attacks on the double bond to generate an alkyl radical on the more substituted carbon atom.
4) The alkyl radical abstracts a hydrogen atom from HBr to generate the product (2-Bromo-1-phenylpropane) and a bromine radical.
5) The bromine radical generated in Step 2 goes on to react with another molecule of alkene in Step 1, continuing the chain.