.
By standing on formal positions of the English language, I can (and I should) interpret the condition
as if Amy is 5 times as old as James
Let x = the James' age; then the Amy's age is 5x, according to my interpretation.
Then I can write this equation
(5x - 3) + (x-3) = 54
6x = 54 + 6 = 60
x = 60/6 = 10.
So, my answer is: Amy is 5*10 = 50 years.
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It is very difficult question: how to interpret.
Formally, English requires exactly this interpretation.
But, practically, in the everyday life, another interpretation just prevales.
The TRUTH is: in your mathematical composing and writing NEVER USE this form
"X is 4 times older than Y",
since it ALWAYS leads to confusing and misinterpretation.
Use this equivalent phrasing
"X is 5 times as old as Y".
instead. Then everybody will understand you by an UNIQUE WAY, and you will avoid misunderstanding.