(1-0.1)÷25分之9
=0.9x25/9
=2.5
12分之5-12分之5÷6分之5×3分之2
=5/12-5/12x6/5x2/3
=5/12-5/12x4/5
=5/12-4/12
=1/12
如果本题有什么不明白可以追问,
如有其它问题,请谅解,