Answer:
The first ratio is
[tex]1USD : 1 \£[/tex]
That is, 1 US Dollar equals 1 British Pound.
Then, the last ratio is
[tex]1USD:0.7\£[/tex]
Which means that for one US Dollar you would get 70 cents of a British Pound.
As you can see, the second represents a devaluation of the US Dollar against the British Pounds. It has a lower value.
