初一数学填空题和计算题（过程要写清）.1/4-2/15+2/3+1/5-5/6-3/4

1/4-2/15+2/3+1/5-5/6-3/4
=1/4-(1/3-1/5)+1-1/3+1/5-(1/2+1/3)-(1-1/4)
=1/4-1/3+1/5+1-1/3+1/5-1/2-1/3+1+1/4
=1+1-1/2-3*(1/3)+1/4+1/4+2*(1/5)
=2-1/2-1+1/2+2/5
=1+2/5
=7/5

1/4-2/15+2/3+1/5-5/6-3/4
=(1/5-2/15)+(1/4-3/4)+(2/3-5/6)
=1/15-(1/2+1/6)
=1/15-2/3
=-9/15
=-2/3