Graphics, Why do they Print out Darker then how it orginally Is?

Greetings..
     Well, I have a Problem. I have a interview soon, and I need to print out 
my graphics from the computer, but everytime I do so, it prints out darker 
than its suposed to be. Some pictures, you cannot even tell what it is.. 
Anyone know Why? or anyway to fix it?

Thank you very much,
-Jenny

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