4.75x4又3/4+4有3/4+4又3/4x4又1/4= 3/4x58+58除以4-64x1/4= 73.8除以9+7

.75x4又3/4+4有3/4+4又3/4x4
=（75+1+4）*4又3/4
=80*4+80*3/4
=320+60
=380
3/4x58+58除以4-64x1/4
=1/4*58*3+1/4*58-64*1/4
=1/4*（164+58-64）
=1/4*158
=39.5
73.8除以9+73.8除以1又1/8
=73.8*1/9+73.8*8/9
=73.8*（1/9+8/9）
=73.8
666.66x7778+333.33x4444
=666.66*7778+666.66*2222
=666.66*(7778+2222)
=666.66*10000
=6666600
（1+1/2+1/3+1/4+1/5）x（1/2+1/3+1/4+1/5+1/6）-（1+1/2+1/3+1/4+1/5+1/6）x（1/2+1/3+1/4+1/5）
=(1/2+1/3+1/4+1/5+1/6）+（1/2+1/3+1/4+1/5）*（1/2+1/3+1/4+1/5+1/6）-（1/2+1/3+1/4+1/5）-（1/2+1/3+1/4+1/5+1/6）*（1/2+1/3+1/4+1/5+）
=0