29/20 1/2mx-3/5=1/2(x-3/4)
1/2mx=1/2(x-3/4)+3/5
1/2mx=1/2x-3/8+3/5
1/2mx=1/2x+9/40
mx=x+9/20
m=1+9/20
m=29/20
m为负数时答案-29/20