It is 30/200, which can be simplified, if you so wish.
30/20
10% of £3 = 30p
30p / 50p = 30/50 = 3/5
1/6
It is 1/30.
3/10
1/6
3/10 ths
15 percent !... or 3/20
One - tenth.
3 tenths (3/10)
2/1,000,000,000,000 = 1/500,000,000,000
It shouldn't cost more than 50 cents or 30p in Great British Pounds.