An example of a $$bull spread$$ strategy involves: $(1)$ Buying one call on IBM stock with X $=$ $$80,$ and C $=$ $$20\mathrm{.}99$ and $(2)$ Write $($or sell$)$ one call on IBM stock with X $=110$ and C $=2\mathrm{.}24.$ What are its profit, given that the stock price in one month can only be $$0,$ $$15,$ $$30,$ $$45,$ $$60,$ $$75,$ $$90,$ $$100,$ $$120,$ $$135,$ $$150,$ $$165,$ or $$180?$ Please also draw a graph showing this. And answer: Why do we call it a bull spread? $($In Excel$)$