<span>29+10j= -11
</span><span>29+10j - 29 = -11 - 29 (subtract 29 to both sides)
10j = -40
10j/10 = -40/10 (divide both sides by 10)
j = -4
</span>
It would be: 420 + (420 * 17.5%)
= 420 + (420 * 0.175) [ 17.5% = 0.175 ]
= 420 + 73.5
= 493.5
In short, Your Answer would be <span>£493.5
Hope this helps!</span>
At around 20'000ft. and higher.