$\text{Theo đề bài ta có:}$
$\text{332 : x dư 12 => 332 - 12 = 320 $\vdots$ x (x > 12)}$
$\text{715 : x dư 15 => 715 - 15 = 700 $\vdots$ x (x > 15)}$
$\text{Suy ra x ∈ ƯC (320, 700)}$
$\text{Ta có: 320 = $2^{6}$ . 5}$
$\text{700 = $2^{2}$ . $5^{2}$ . 7}$
$\text{=> ƯCLN (320, 700) = $2^{2}$ . 5 = 20}$
$\text{ƯC (320, 700) = Ư (20) = {1 ; 2 ; 4 ; 5 ; 10 ; 20}}$
$\text{Vì x > 15 nên x = 20}$
$\text{Vậy x =}$ 20