You can't fix the worse problem first. You'll get nowhere if you look at this as a collection of individual problems. You won't find a country that has a high standard of living, high employment, and a good educational system, but can't get mosquito nets for their beds.

You can't even begin to think about the issue unless you understand some complex-system domain, preferably economics or ecology. As a crude analogy, an economy is like the framework of a large and complicated tent. If the tent has fallen, you can't pick up individual pieces and put them back in place. It will fall down again as soon as you let go.

Trying to "fix the worst problem first" is the philosopher's solution. A philosopher looks for the biggest questions, tackles them directly, and never solves them. A scientist looks for questions that are solvable. Science also proceeds at its edges.