`3.5^2-16:2^3+4^2+3^2-2^4. 5`
`= 3.25 - 16:8 + 16 + 9 - 16.5`
`= 75 - 2 + 16 + 9 - 80`
`= 18`
$\dfrac{6.8.12^2 - 24.88}{2^4 . 5^3} = \dfrac{2^8 . 3^3 - 2^6 . 3 . 11}{2^4 . 5^3} = \dfrac{2^6 . 3(4 . 9 - 11)}{2^4 . 5^3} = \dfrac{4.3.25}{5^3} = \dfrac{12}{5}$
$\dfrac{7.8.132 - 28 . 138}{2^6 . 5^3} = \dfrac{2^5 . 3 . 7 . 11 - 2^3 . 3 . 7 . 23}{2^6 . 5^3} = \dfrac{2^3 . 3 . 7 ( 4 . 11 - 23)}{2^6 . 5^3} = \dfrac{3.7.21}{8.5^3} = \dfrac{441}{1000}$