Question

If one U.S. dollar is worth 0.690 English pounds, how many U.S dollars are needed to purchase an item that costs 350 dollars?

Answer 1

Something is wrong with your question, it must be 350 pounds.
So the approach for this question would be the use of unit analysis.
1 us dollar = 0.690 pounds
350 pounds * 1 dollar / 0.690 pounds= 507.24 dollars.
to check:507.24 dollars x 0.690 pounds / 1 dollars = 350 pounds