Please help me friends

Please help me friends Calculate the current drawn by the primary of a transformer, which steps down 200 V to 20 V to operate a device of resistance 20 Q. Assume the efficiency of the Uans- O. 125 A1 former to be 80%.

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May be this is the way to answer

As per the question,
Potential provided by primary= 200V
V of secondary = 20V
20V is the final potential obtained which will run the 20ohm resistor
So R= 20ohm
I=V/R = 20 V/20ohm = 1 A
Now efficiency of a transformer is given by,
n = Vs x Is/Vp x Ip that is output/input
80/100 = 20*1/200*Ip
Ip= 1/8
Therefore current drawn by the primary of a transformer is 0.125A.

I hope this helps you.... Regards