There are a batch of comic books in the library of Xinhua Primary School. After donating 3/8 of these comic books to Hope Primary School last year, another 378 comic books were purchased. At this time, the number of comic books in the school library has increased by 15%. How many comic books did the school library originally have?
新华小学图书室有一批连环画，去年把这批连环画的(3/8)捐赠希望小学后，又添购了378本连环画，这时学校图书室的连环画本数比原来多了15%．学校图书室原来有连环画多少本？
<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(3/20) - 1</gadget>
<output>-17/20 = around -0.85</output>

<gadget id="calculator">(3/8) + 1 + (-17/20)</gadget>
<output>21/40 = around 0.525</output>

<gadget id="calculator">378 / (21/40)</gadget>
<output>720</output>

<result>720</result>