If a device(consisting of 3 bulb) is connected in series then current will divide among all three bulbs and if same device connected in parallel series then current of same amount will pass through all the three bulbs..
soo if a device of three bulbs connected in both series and parallel then it will behaving like a series in which current will divide across 4 bulb(3 of series and 1 of parallel or we can say that current of same amount pass in parallel comb. so in parallel we count only one bulb).
Hope it is helpfull....
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