Alligation or mixture in shorcuts methods

How to learn alligation or mixture in shorcuts methods
1. Alligation : it is the rule that enables us to find the ratio in which two or more ingrediends at the given price must be mixed to produce a mixture of a desired price
2. Mean price : the cost price of a unit
3. Rule of Alligation : If two ingrediends are mixed, then..
(cheaper quantity ) : (dearer quantity ) = (d-m) : (m-c)


Ex. 1. in what ratio must rice at Rs. 9.30 per kg be maxed with rice at Rs. 10.80 per kg so that the
mixture be worth Rs. 10 per kg ?