Let amount of 3 types of rice be x,y and z, respectively.

Using rule of alligation for x and y

So, x : y = 12 : 84 = 1 : 7

Similarly using the rule of alligation x and z

So, x : z = 132 : 84

= 11 : 7

= 1 : 7/11

On combining the two ratio, we get

x : y : z = 1 : 7 : 7/11

**= 11 : 77 : 7 **