37.6+113/4+62.4+1/4
=(37.6+62.4)+(113/4+1/4)
=100+28.5
=128.5
3x-1/5*9/20=1.56
3x-0.45=1.56
3x=1.56+0.45
3x=2.01
x=0.67
如果本题有什么不明白可以追问,