cost of production fifo method

sir, I have don’t understand only one thing
question is from kaplan book chapter 9
question :

BR Ltd makes a product requiring several successive processes. Details
of the first process for August are as follows:
Opening WIP: 400 units
Degree of completion:
Materials (valued at $19,880) 100%
Conversion (valued at $3,775) 25%
Units transferred to Process 2 1,700 units
Closing WIP 300 units
Degree of completion:
Materials 100%
Conversion 50%
Costs incurred in the period:
Material $100,000
Conversion $85,995
There were no process losses.
Required:
Prepare the process account for August using the FIFO method.

Solution:
Statement of EUs Physical units Materials Conversion
% EUs % EUs
OWIP
completed 400 0 0 75 300
Fully-worked in
process 1,300 100 1,300 100 1,300
CWIP 300 100 300 50 150
______ ______ ______
Total 2,000 1,600 1,750
—— —— ——
Costs $100,000 $85,995
Cost per EU $62.50 $49.14
Valuation of transfers to Process 2:
OWIP value from last period = $19,880 + $3,775 = $23,655
OWIP completed this period (conversion only) = 300 × $49.14 = $14,742
Fully-worked current period
Materials = 1,300 × $62.50 = $81,250
Conversion = 1,300 × $49.14 = $63,882
Total valuation of transfers to Process 2 = $183,529
Valuation of CWIP:
Materials = (300 × $62.50) = $18,750
Conversion = (150 × $49.14) = $7,371
Total valuation of CWIP = $26,121
Process 1 Account
Unit $ Units $
OWIP 400 23,655 Transferred to 1,700 183,529
Process 2
Materials 1,600 100,000 CWIP 300 26,121
Conversion 85,995
––––– –––––– ––––– ––––––
2,000 209,650 2,000 209,650
––––– –––––– ––––– ––––––

sir i don’t understand this line : OWIP completed this period (conversion only) = 300 × $49.14 = $14,742

how did we came up with 300 units for opening work in process completed this period.
I watched the lectures and was not able to find this line where we have to find out the opening work in process