Uncle Zhang went to the stationery store and bought 3 pens at 18 yuan each. He paid the salesperson 100 yuan. How much should he get back? (Solve with a comprehensive formula)
张叔叔到文具用品店买了3支钢笔，每支18元，他付给营业员100元，应找回多少元？(用综合算式解答)
<gadget id="calculator">18 * 3</gadget>
<output>54</output>

<gadget id="calculator">100 - 54</gadget>
<output>46</output>

<result>46</result>