To make a pudding, you need $$2$$ ounces of flour and $$10$$ ounces of milk. You have $$10$$ ounces of flour and want to make as many puddings as possible. How much milk do you need? 
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The ratio of flour to milk is $$2:10$$ or $$1:5$$. With $$10$$ ounces of flour, you could make as many as $$5$$ puddings. At the same time, you need $$50$$ more ounces of milk. The ratio of flour to milk is $$10:50$$, or $$1:5$$. 