Either you have never visited a third world nation in your entire life, or you are living in the 1990s. There are poor people in third world nations, and there are lots of them (hundreds of millions). But there are very few who can't afford food twice a day. Times have changed and poverty is in decline, even in these third world nations. They may not be able to afford the luxuries, but at the same time most of them can afford the basic things such as food and electricity.
I think a third world country is considered as one in my opinion if the country has a high poverty rates, resource deficiency, high crime and corruption rates, wealth disparity is large and unstable finances. How can you say that poverty is declining? Are you working on surveys about the third world country to confirm that the poverty rate is declining? Why is in my country a lot of people in the poverty line can't afford those basic necessities that you are stating? Because according to this
article the poverty index for two years is 9.1 to 9.4 percent which is a considerable increase compared to 9.2 percent in 2017. This
study also shows that 3 billion of people lives under 2.5 USD a day so is the poverty really declining? To answer the title, I would say that it can be solved but we have to move aside our differences and remove corruption in our governments and change the mentality of the masses but given that we haven't solved poverty for a long time, I don't think that we will be able to solve it.