18 more than 6 in a mathematical expression will be 18 + 6 or 6 + 18. Because we are adding 6 to 18 or 18 to 6.
The answer is 2
------------------------
Probability a gets a head = 1/2
.. .. .. b .. .. ... .. = P(a gets tail) * 1/2 = 1/2 * 1/2 = 1/4
.. ... . .. c .. .. .. .. . = P(and and b gets tail) * 1/2 = 1/4 * 1/2 = 1/8
4/5 is the the fraction of a pound is eighty pence