the planes purchased should be the longer$-$range $787$; $(4)$ the annual maintenance budget is to be no more than $$8$ million; $(5)$ the annual maintenance cost per $787$ is estimated to be $$800,000,$ and it is $$500,000$ for each $767$; and $(6)$ each $787$ can carry $125,000$ passengers per year, whereas each $767$ can fly $81,000$ passengers annually. Formulate this as an integer programming problem to maximize the annual passenger$-$carrying capability. What category of integer programming problem is this? Solve this proble