Xiao Ming scored 98 points in the second unit test, which is 18 points higher than the first unit test score. How many points did Xiao Ming score in the first unit test?
小明第二单元考了98分，比第一单元考试成绩提高了18分，小明第一单元考了多少分．
<gadget id="calculator">98 - 18</gadget>
<output>80</output>

<result>80</result>