Question 1165880
Think about the fraction for going from one concentration to the other concentration using the available chocolates.   You could use {{{4/10}}} or {{{6/10}}}.


26% is closer to 30% than to 20% so the distributor wants {{{6/10}}} of the mixture to be of the 30% fat content chocolate.  (That would be, in this example, 60 kilograms.)


Or you can use algebra.