Undertake an option strategy that consists of:
- Sell 1 Put with stike K =75;
- Buy 3 Puts with strike K = 85;
- Sell 2 Puts with strike K = 90.
1) Plot the resulting net payoff as a function of S(T).
2) Is the net initial premium (i.e. original cost of the strategy) positive, negative or zero (or underdetermined)? Explain your answer.