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If:

then calculate:

Solution
Adding lines ...1 and ...2 gives:

We notice expression (a+b).
But how to eliminate the roots?
Say:

this changes the equations before into:

which reminds us of:
(a+b)3 = a3 + 3a2b + 3ab2 + b3
So, multiply line ...5 by 3 and add line ...4 .
The result is:

Now substitute ..6 at line ...3 and insert factor 9/5 :

The answer is 73.
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