Question

2又8分之1成9分之4除(1减六分之1)、15分之8除8加15分之7成8分之1、2减15分之7成24分之5简算

Answer 1

2又8分之1成9分之4除(1减六分之1)
=17/8×4/9÷(1-1/6)
=17/8×4/9÷5/6
=17/8×4/9×6/5
=(17×4×6)/(8×9×5)
=(17×8×3)/(8×3×15)
=17/15

15分之8除8加15分之7成8分之1
=8/15÷8+7/15×1/8
=8/15×1/8+7/15×1/8
=(8/15+7/15)×1/8
=1/8

2减15分之7成24分之5
=2-7/15×5/24
=2-(7×5)/(15×24)
=2-(7×5)/(5×72)
=2-7/72
=144/72-7/72
=137/72