Guys,

Just looking through a chapter on Ratio's and one of the examples is:

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Q: Divide a mass of 380 kg in the ratio 3/4 : 1/5

S: It is simpler to work with whole numbers, so first of all we produce and equivalent ratio by multiplying each term, first by 4, and then by 5 to give

3/4 : 1/5 =3 : 4/5= 15:4

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I understand how to get from 3/4 : 1/5 to 15 : 4 by the lcm but I'm not sure where the3 : 4/5comes from, thats the step I'm missing.

Thanks