Answer
The two numbers are 4.5 and 7.5
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Step-by-step explanation
Two numbers are in the ratio 5:3 means that the larger number is 5x and the smaller is 3x, for some positive real number x.
They differ by 3, so 5x-3x = 3. That equation solves to x = 3/2 = 1.5
The numbers are therefore
5x = 5*1.5 = 7.5
3x = 3*1.5 = 4.5
The ratio 7.5:4.5 simplifies to 5:3 when you divide both parts by 1.5
Note how 7.5-4.5 = 3, which confirms the other requirement.