Answer:
The answer to you problem is, 30%
Explanation:
First lets do some subtraction:
400 - 280 = 120.
So we want to know what is half:
400 / 2 = 200.
80 units away from 200.
10% of 400 = 40.
120 / 400 = 0.3. Make it in percetage:
0.3 x 100 = 30%
? x 100 = ? <--- Use this formula to find out percetage.
Thus the answer to your problem is, 30%