Answer:
It's just a simultaneous equation
Explanation:
Let a big bag of sugar = x
Let a small bag of flour = y
x+x+y = 12kg
2x+y = 12kg ... 1
x-y = 2kg ... 2
Add 1 and 2
2x+y = 12
+
x -y = 2
3x = 14
x = 14/3 = 4.66
Substitute value of x into 1
2(4.66)+y = 12
9.333 + y = 12
12 - 9.333= 12
y = 2.66
Hope you understand it
And I hope my answer was of help to you.