x-(x-1)/3=7-(x+3)/5两边乘1515x-5x+5=105-3x-910x+5=96-3x10x+3x=96-513x=91x=91÷13x=7
5分之2（k+3）=（3/2）k-三分之2（k-7）两边乘3012(k+3)=45k-20(k-7)12k+36=45k-20k+14045k-20k-12k=36-14013k=-104k=-8
等于7时
