Verified Answer :

10% of 400 = 40
1% of 400 = 4
0.1% of 400 = 0.4

(3 x 1%) + (2 x 0.1%) = 3.2%
3.2% = 12.8 
Answer is 412.8 pounds

slevo

to get 3.2% : 400 x  \(\frac{3.2}{100}\) = 12.8

12.8 + 400 = £412.80