Equivalent units

The following data relate to a process for last month:

Opening inventory 200 units (70% complete)

Completed output 2450 units

Closing inventory 300 units (40% complete)

Using the fifo method, what were the equivalent units of production last month?

Sir I can’t figure out what we are supposed to do here, i mean i calculated the answer this way

O.P inv equiv units= 200×30%=60

C.L inv equiv units= (300×40%)=120

For production we simply deduct output from opening inv and adding closing inv eventually so my answer is = 2450-60+120=2510

But the actual answer provided is 2430,

And they’re doing it this way

O.p inv equiv units=(200×70%)=140

The rest is same, 2450-140+120=2430

I didn’t understand why are we calculating opening with 70%? Though opening still has 30% to be completed, 70% is already completed.

I read your answer to this question in different post, you deducted completed units first from opening inv 2450-200= 2250 and adding all the calculation just like i did opening with 30% and ending with 40%, but you add altogether, sir why did you deduct completed output units from opening inventory? Isn’t completed output already deducted from opening? Because to find transferred output we add opening inventory and deducting from closing, which gives us output and we deduct it again with opening to get transferred completed output.

Also sir to find production, aren’t we going to add output with closing and deduct from opening? Please sir explain me this question where am i doing wrong