MIXT Ratio, or Proportion, is when the sum of the antecedent and consequent is compared with the difference of the antecedent and consequent;

\text{as if } \begin{cases} 4 : 3 :: 12 : 9 \\ a : b :: c : d \end{cases} \text{then } \begin{cases} 7 : 1 :: 21 : 3 \\ a + b : a - b :: c + d : c - d \end{cases}