30 in the ratio 3:2
3:2....added = 5
3/5(30) = 90/5 = 18
2/5(30) = 60/5 = 12
so 30 in the ratio 3:2 is 18:12
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31.50 in the ratio 3:4
3:4...added = 7
3/7(31.50) = 94.5/7 = 13.50
4/7(31.50) = 126/7 = 18
31.50 in the ratio 3:4 is 13.50:18