The answer is 63.75
How i got this is first you need to turn 15% into a decimal to do that you need to move the decimal from the hundrith place or the second number which in this case it would be 5 in the 15%
Now that you know the decimal all thats left to do is to just multiply .15 to £425
£425x.15= £63.75 <--- 15% of £425