ANSWER
30 kilograms of the 20% fat-content chocolate was mix with 70 kilograms of the 40% fat-content chocolate
Step-by-step explanation
Let the amount of the 20% fat-content chocolate mixed be x.
Let the amount of the 40% fat-content chocolate mixed be y.
100 kilograms of the 34% fat-content chocolate was created, so:
x + y = 100 _____(1)
The 20% fat-content chocolate and the 40% fat-content chocolate were mixed to create a 34% fat-content chocolate.
This means that:
20 * x + 40 * y = 100 * 34
=> 20x + 40y = 3400 _____(2)
From (1):
x = 100 - y
Put that in (2):
20(100 - y) + 40y = 3400
2000 - 20y + 40y = 3400
2000 + 20y = 3400
Collect like terms:
20y = 3400 - 2000 = 1400
y = 1400 / 20
y = 70 kilograms
Recall that:
x = 100 - y
=> x = 100 - 70
x = 30 kilograms
Therefore, 30 kilograms of the 20% fat-content chocolate was mix with 70 kilograms of the 40% fat-content chocolate.