giúp mình câu b bài 2 ạ nhanh ạ mình đg cần gấp ạ

`# Traam`

`a )`

`21/47 + 9/45 + 26/47 + 4/5`

`= 21/47 + 26/47 + 9/45 + 4/5`

`= 47/47 + 1/5 + 4/5`

`= 1 + 1`

`= 2`

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`b )`

`( 5^4 . 20^4 )/( 25^5 . 4^5 )`

`= ( 5^4 . 4^4 . 5^4 )/( (5^2)^5 . 4^5 )`

`= ( 5^4 . 5^4 . 4^4 )/( 5^2.5 . 4^5 )`

`= ( 5^8 . 4^4 )/(5^10 . 4^5 )`

`= 1/(5^2 . 4 )`

`= 1/(25.4)`

`= 1/100`