Hello Tayba,
They already took the BWIP into Consideration when they Took the Total amount of Completed Units,
Completed Units Equals (BWIP + Started & Completed) or (BWIP + Started - EWIP)
In the Weighted-Average Method Qs, you have to look for the Completed units as a Total and Forget about the beginning WIP, Because he only Considers the Completed & EWIP as An " Average ", that's why it's called Weighted average, So in this case,
Completed units are equal 184,000
EWIP = 48,000 * 40% = 19,200
So the Total EUP = 203,200
Dividing all the beginning and Incurred CC(DL +MOH) = 609,600 $
It will result in (609,600$/203,200)= 3$ per EUP