ratios
posted by tish on .
Martha is flying to England for a visit. She intends to exchange her U.S. dollars for English pounds. The exchange rate allows 60 pounds for every 100 U.S. dollars. How many pounds will she get if she exchanges $450 U.S. dollars for pounds?
60:x = 100:450 ( this is how I was trying to work this out but again, I don't the answer in my book ).
Help greatly appreciated.
Thanks

Your ratio is wrong. Put the pounds on top and the dollars on the bottom. Or you could reverse that.
60/100 = x/450
Cross multiply and solve for x.
100x = 27,000
x = 270 pounds 
The book I am learning from gives an answer of 750 pounds. I am working out of Mathematics Made Simple fifth edition. It doesn't show the work. It shows me one way of doing certain problems and then changes. frusterating? Thank you for your help.

Either you've copied the problem wrong, or your book's answer is wrong.
The problem states that you for 60 pounds, you pay $100. Therefore you'll get a smaller number of pounds than dollars.
Look at it this way.
Pay $100; get 60 pounds
Pay $200; get 120 pounds
Pay $300; get 180 pounds
Pay $400; get 220 pounds