Answers

The simplest form of -18/21 is -6/7.

Steps to simplifying fractions

1. Find the GCD (or HCF) of the absolute values of both numerator and denominator
   GCD of 18 and 21 is 3
2. Divide both the numerator and denominator by the GCD
   -18 ÷ 3/21 ÷ 3
3. Reduced fraction: -6/7
   Therefore, -18/21 simplified to lowest terms is -6/7.

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