Mixed ratio or compound ratio of 6:5,5:3,4:9 will be
8:9
Mixed ratio or compound ratio is genrated by taking the product of the antecedents of all the ratios as antecedents and the product of the consequents of all the ratios as consequents.
so by doing multiplication of antecedents and consequents
we get , 6x5x4 : 5x3x9
=2x4:9 =8:9