设新涂料每千克售价是x元,
100/(x+3)+240/(x-1)=(100+240)/x
同时乘以（x+3）(x-1)x得
100(x-1)x+240（x+3）x=340（x+3）(x-1)
去括号的100x2-100x+240x2+720x=340x2+680x-1020
移项合并同类项的60x=1020
x=17