Consider the parallelogram with vertices \((10,45),\) \((10,114),\) \((28,153),\) and \((28,84).\) A line through the origin cuts this figure into two congruent polygons. The slope of the line is \(m/n,\) where \(m_{}\) and \(n_{}\) are relatively prime positive integers. Find \(m+n.\)

(第十七届AIME1999 第2题)