Xiao Liang originally had some pictures, his friend gave him 8 more, he gave his younger brother 5, and later bought 23 more, making a total of 54 pictures. How many pictures did Xiao Liang have? (Solved by inversion method)
小亮原来有一些画片，朋友又送给他8张，他给弟弟5张，后来又买了23张，这是共有54张画片．小亮原来有多少张画片？(用倒推法解决)
<gadget id="calculator">54 - 23</gadget>
<output>31</output>

<gadget id="calculator">5 - 8</gadget>
<output>-3</output>

<gadget id="calculator">31 + (-3)</gadget>
<output>28</output>

<result>28</result>