`25 - 15 : 5= 25 - 3 =22`

`101 × (16 – 7)= 101 xx 9=909`

`40 + 8 : 2= 40 + 4=44`

`48 : (8 : 2)= 48 : 4=12`

\(\dfrac{6}{7}+\dfrac{5}{8}:5-\dfrac{3}{16}.\left(-2\right)^2=\dfrac{6}{7}+\dfrac{5}{8}:5-\dfrac{3}{16}.4=\dfrac{6}{7}+\dfrac{1}{8}-\dfrac{3}{4}=\dfrac{5}{56}\)

\(\dfrac{2}{3}+\dfrac{1}{3}.\left(-\dfrac{4}{9}+\dfrac{5}{6}\right):\dfrac{7}{12}=\dfrac{2}{3}+\dfrac{1}{3}.\dfrac{7}{18}:\dfrac{7}{12}=\dfrac{2}{3}+\dfrac{2}{9}=\dfrac{8}{9}\)

\(\frac{7^2}{2.9}+\frac{7^2}{9.16}+...+\frac{7^2}{65.72}\)

\(=7^2\left(\frac{1}{2.9}+\frac{1}{9.16}+...+\frac{1}{65.72}\right)\)

\(=\frac{7^2}{7}\left(\frac{1}{2}-\frac{1}{9}+\frac{1}{9}-\frac{1}{16}+...+\frac{1}{65}-\frac{1}{72}\right)\)

\(=7\left(\frac{1}{2}-\frac{1}{72}\right)\)

\(=7.\frac{35}{72}\)

\(=\frac{245}{72}\)

a) $2^3\cdot3^2+7^{16}:7^{14}-2022^0$

$=8\cdot9+7^2-1$

$=72+49-1$

$=120$

b) $2x-9=3\cdot(-7)$

$\Rightarrow2x-9=-21$

$\Rightarrow2x=-21+9$

$\Rightarrow2x=-12$

$\Rightarrow x=-12:2=-6$

\(9!-8!-7!.8^2\)

\(=362880-40320-5040.64\)

\(=362880-40320-322560\)

\(=322560-322560\)

\(=0\)

9!-8!-7!.8^2=0

362880-40320-5040.64=0