Question 1203368
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Irene bought 10 pens with 2/5 of her money. If she bought another 24 pens then she would need $18 more. 
What is the amount of money she had left after buying the 10 pens.
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        Such problems on "shortage the money" are traditionally considered 
        as entertainment Math problems.

        Therefore, I will give you MENTAL solution below.



<pre>
Since Irene bought 10 pens with 2/5 of her money, it means that
she could buy 15 more pens for her remaining 3/5 of money.

But the problem said that if she bought additional 24 pens (additional to that 10 pens), 
she would be $18 short.
It means that 24-15 = 9 extra pens cost $18. Hence, each pen costs 18/9 = 2 dollars.


Great (!) Half of the problem is solved. The rest is just easy.


One pen costs 2 dollars; hence, 15 pens cost 30 dollars, 
and it is the amount of money she had left after buying the 10 pens.


<U>ANSWER</U>.  After buying 10 pens, Irene had left 30 dollars.
</pre>

Solved.



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The solution by @josgarithmetic is incorrect, as usual.


Therefore, for the peace in your mind and for safety of your mind, ignore his post.