40%x-1/4=7/1240/100分数化简就是2/5原式=2/5x-1/4=7/12 2/5x=7/12+1/4后两项通分,分母为12,7/12+3/12=10/122/5x=10/12两边乘以5/2, 最后x=50/24
40%x-1/4=7/122/5x=7/12+1/42/5x=5/6x=25/12
40%x-1/4=7/122/5x-1/4=7/122/5x=5/6x=25/12