六年级下册数学题目求大神解答.

0.25×64×125%
=(0.25×8)×(8×0.125)
=2×1
=2
[8/15—(7/12—2/5)]×15/14
=[8/15—11/60]×15/14
=21/60×15/14
=3/8
6.35×0.75＋4.65×75%—3/4
=6.35×3/4＋4.65×3/4—3/4×1
=(6.35+4.65—1)×3/4
=(11—1)×3/4
=10×3/4
=15/2
1/2：3/8=x：0.8
3/8x=0.8x1/2
x=0.4除3/8
x=16/15