Mr kong earns $850 per month. He spents $500 and saves the rest. What is the ratio of the amount of money saved to the amount of money earned?

The amount of money saved is $850 - $500 = $<<850-500=350>>350.

The ratio of the amount of money saved to the amount of money earned is $350/$850 = <<350/850=0.4117647058823529>>0.4118, which can also be written as 41.18%. Answer: \boxed{0.4118}.