`color{pink}{Harry}`

`a) (2^12 . 3^5 – 4^6 . 3^6)/(2^12 . 9^3 – 8^4 . 3^5)`

`= (2^12 . 3^5 – 2^12 . 3^6)/(2^12 . 3^6 – 2^12 . 3^5)`

`= [2^12 . (3^5 – 3^6)]/[(2^12 . (3^6 – 3^5)`

`= (3^5 – 3^6)/(3^6 – 3^5)`

`= -486/486`

`= -1`

`----------`

`b) (8^10 + 4^10)/(8^4 + 4^11)`

`= (2^30 + 2^20)/(2^12 + 2^22)`

`= [2^20 . (2^10 + 1)]/[2^12.(1+2^10)`

`= 2^20/2^12`

`= 2^8`

`= 256`