Lenny bought 20 boxes of pens. Each box contained  5 pens. She gave 40% of the pens to her close friends and one-fourth of what's left to her classmates. How many pens were left for Lenny?
Lenny has 20 x 5 = 
<gadget id="calculator">20*5</gadget>
<output>100</output>
100 pens.
She gave her close friends 100 x 40% = 
<gadget id="calculator">100*40*.01</gadget>
<output>40</output>
40 pens.
So, 100 - 40 = 
<gadget id="calculator">100-40</gadget>
<output>60</output>
60 pens were left.
Half of 60 is 60/4= 
<gadget id="calculator">60/4</gadget>
<output>15</output>
15 pens.
Thus, Lenny has 60 - 15 = 
<gadget id="calculator">60-15</gadget>
<output>45</output>
45 pens left.

<result>45</result>