In a mathematics competition, more than 200 people from a certain school participated, among them (1/18) scored less than 70 points, and (1/7) scored less than 80 points. (1/4) reached 90 points. So how many people have scores between 80 and 89?
一次数学竞赛，某校有200多人参加，其中(1/18)的人不到70分，(1/7)的人不到80分．(1/4)的人达到90分．那么得分在80分至89分的有多少人．
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/7) + (1/4)</gadget>
<output>11/28 = around 0.392857</output>

<gadget id="calculator">1 - (11/28)</gadget>
<output>17/28 = around 0.607143</output>

<gadget id="calculator">252 * (17/28)</gadget>
<output>153</output>

<result>153</result>