To get a 100 kilograms of a 48% fat content chocolate how many kilograms of a 30% and 50% mix should be used

A kilogram %30 chocolate,

b kilogram %50 chocolate,

a+b = 100 kilogram chocolate,

48. (a+b) = 30. a + 50. b

48a + 48b = 30a + 50b

18a = 2b

b = 9a

a+b = a + 9a = 10a = 100 kg

a = 10 kg

b = 9. a = 90 kg

You should use,

10 kg %30 chocolate,

90 kg %50 chocolate