We simplify the radicals first and then collect together like terms.

`3sqrt(125) - sqrt(20) + sqrt(27)`

`= 3sqrt(25 times 5) - sqrt(4 times 5) + sqrt(9 times 3)`

`=3(5sqrt(5)) - 2 sqrt(5) + 3sqrt(3)`

`=13sqrt(5) + 3sqrt(3)`

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