Need another help with a math problem

Go backwards. Start with a hundred and do the opposite of what's been done.

Draw a circular pizza cut into 12 slices
Shade out portions for 1/6 and 1/2 of the remaining pizza.
Write £100 on the piece remaining by dividing it equally across its slices.
Now you have the value of one slice...therefore the whole lot.

and then make sure you convert pounds to dollars- I think the exchange rate is at £1 to $1.35 right now (as per the newspaper yesterday anyway).

*sorry fresco couldn't resist

These days, nobody can afford a whole pizza over here !

If I understand you correctly, "the remaining money" is 5/6 of the original total. Half of this was spent on the horseback riding, leaving 5/12 of the original amount, and thats equal to $100.

(5/12)X = $100
X = 12/5 * $100 = $1200/5 = $240.