1、400÷25-400÷30
=16-40/3
=48/3-40/3
=8/3米
2、0.8×{[(2/2)²-0.8²]×3.14×60}
=0.8×{[1-0.64]×3.14×60}
=0.8×{0.36×3.14×60}
=0.8×67.824
=54.2592
≈54.26千克
1、400÷25-400÷30
=16-40/3
=48/3-40/3
=8/3米
2、0.8×{[(2/2)²-0.8²]×3.14×60}
=0.8×{[1-0.64]×3.14×60}
=0.8×{0.36×3.14×60}
=0.8×67.824
=54.2592
≈54.26千克