50:75. 18:27

To simplify the ratios \(50:75\) and \(18:27\):

1. For \(50:75\):

   • Find the greatest common divisor (GCD) of 50 and 75. The GCD is 25.
   • Divide both numbers by 25: \[ \frac{50}{25} : \frac{75}{25} = 2 : 3 \]

2. For \(18:27\):

   • Find the GCD of 18 and 27. The GCD is 9.
   • Divide both numbers by 9: \[ \frac{18}{9} : \frac{27}{9} = 2 : 3 \]

Thus, both ratios simplify to \(2:3\).