Find the amount of the loss: Amount of insurance purchased 400,000 coinsurance requirement 80% property's insurable value at time of loss 840,000 property's insurable value when policy was purchased 700,000 amount of loss paid by the insurer 340,000

Please show steps!! no excel. Thanks !

PS: answer that using:

700,000 * 0.8 = 560000

476000= 340000 *(560000/400000)

marked as wrong by my prof