Edward spent $ 49. Then he received $ 45 from his friend. Now he has $ 14. How much did Edward have before he spent his money?
Edward spent $49. So we know that he had at least $49 to spend. 

Then he received $45 from his friend. So now we know that he has at least $45 + $49, or $94. 

But we know that he only has $14. So we can say that he had $94 - $14, or $80, before he spent his money.