The Answers

Answer to Question 1

• (a.)
  133 is the starting amount and you subtract 3 because that is the basic charge for the transaction.
  133 - 3 = 130
  Then, you multiply by 2.5 because that is the currency exchange rate.
  130 * 2.5 = 325
  Frederick would buy 325 swiss francs with 130 GBP.
  
  
• (b.)
  Set the equation up by using the equation from part a where three ( the base transaction charge) is subtracted from the given amount of GBP in this case the unknown variable, b, and then multiplying by the currency exchange rate to determine the amount of CHF recieved in the end ( a variable that is given as 430 in the problem).
  (b-3)2.5 = s
  (b-3)2.5 = 430
  Multiply 2.5 by each item in the parenthesis
  2.5 b - 7.5 = 430
  add 7.5 to both sides
  2.5 b = 437.5
  b = 75
  Frederick exchanged 75 GBP for the 430 CHF.