[tex]\frac{15}{18}\\\\divide\ a\ numetrator\ and\ a\ denominator\ by\ 3\\\\15:3=5;\ 18:3=6\\\\therefore\ \frac{15}{18}=\frac{5}{6}\\\\\frac{25}{30}\\\\divide\ a\ numerator\ and\ a\ denominator\ by\ 5\\\\25:5=5;\ 30:5=6\\\\therefore\ \frac{25}{30}=\frac{5}{6}\\\\conclusion:\frac{15}{18}=\frac{25}{30}\\\\Answer:\boxed{C}[/tex]
