I unit=1000 watt. So 25 unit= 25000 watt per hour.
3 ceiling fan= about (240 watt x 16 hours x 30 days) = 115200 watt.
So you have to pay for (115200-25000)/1000 = 90.2 unit.
So if 1 unit electricity cost about 6 rupees then you have to pay 90.2x6 = 541.20 Taka per month for 3 ceiling fan.
*Meter rent included in ₹6.