Create a bull spread using put options! Assuming X1

Compare the payoff at expiration of the bull spread strategy when created using calls (as we did it in class) and when it is created using puts. Fill in the following tables using ST, X1,X2, 0, -, +, as applicable (capital letters, no subscripts, no spaces)

Bull spread with calls	ST	X1<=ST	X2<=ST
Payoff LC at X1	0	ST-X1	ST-X1
Payoff SC at X2	0	0	X2-ST
Payoff of call option strategy	0	ST-X1	X2-X1
Bull spread with puts
Payoff of put option with X1 strike	?	?	?
Payoff of put option with X2 strike	?	?	?
Payoff of put option strategy	?	?	?

To make the two strategies have the same payoff at expiration, you would also have to invest ________ amount in a risk free T-Bill when establishing the put strategy. (Use a combination of the following, as applicable, without any spaces: PV(), X1, X2, S0).