I have the following model:

m1.dis=arima(diff(diff(log(ts1),lag=12)),order=c(0,1,1),seasonal=list(order=c(0,1,1),period=12))

I would like to know how to plot the correct predictions in the original units because I am trying the following code but it is not working.
I believe that there must be something to account for the differencing.

plot(m1.dis,n1=c(1990,1),n.ahead=36,xlab='Year',type='o',ylab='Discharge (cfs)',transform=exp)


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