Apparently careless in calculating the subtraction, mistook the subtrahend 587 for 578, and the result was 89. What is the correct difference?
明明计算减法时粗心，错把减数587当成578，结果为89．正确的差应是多少？
<gadget id="calculator">578 + 89</gadget>
<output>667</output>

<gadget id="calculator">667 - 587</gadget>
<output>80</output>

<result>80</result>