3. For which moduli $m$ do the congruences $32 \equiv 11(\bmod m)$ and $1000 \equiv -1(\bmod m)$ both hold? In general, what condition must the modulus $m$ satisfy for the congruences $a \equiv b(\bmod m)$ and $c \equiv d(\bmod m)$ to both hold?
3. $m \mid (a-b, c-d)$.

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