The little sloppy miscalculated 30*(□+3) into 30*□+3 due to his carelessness. Please help me to calculate. How much difference is the result he got from the correct result?
小马虎由于粗心大意把30*(□+3)错算成30*□+3，请你帮忙算一算，他得到的结果与正确结果相差多少？
<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<gadget id="calculator">90 - 3</gadget>
<output>87</output>

<result>87</result>