`a, 71 - 933 + x = 3^{3}`
$\Rightarrow$ `-862 + x = 27`
$\Rightarrow$ `x = 27 + 862`
$\Rightarrow$ `x = 899`
$\text{Vậy}$ `x = 899`
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`b, 24 + 5x = 7^{5} : 7^{3}`
$\Rightarrow$ `24 + 5x = 7^{2}`
$\Rightarrow$ `24 + 5x = 49`
$\Rightarrow$ `5x = 49 - 24`
$\Rightarrow$ `5x = 25`
$\Rightarrow$ `x = 25 : 5`
$\Rightarrow$ `x = 5`
$\text{Vậy}$ `x = 5`