`2sqrt{45} + sqrt5 - 3sqrt{80}`
`= 2sqrt{3^2}sqrt5 + sqrt5 - 3sqrt{2^4}sqrt5`
`= 6sqrt5 + sqrt5 - 12sqrt5`
`= -5sqrt5`
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`sqrt{7-4sqrt3} + 2/(sqrt3+1) - 6sqrt{16/3}`
`= sqrt{(sqrt3)^2-4*1sqrt3+(sqrt4)^2} + (2(sqrt3-1))/((sqrt3+1)(sqrt3-1)) - 6sqrt{16}/sqrt3`
`= sqrt{(sqrt3-2)^2} + (2(sqrt3-1))/(sqrt3^2-1^2) - 24/sqrt3`
`= |sqrt3 - 2| + sqrt3 - 1 - 8sqrt3`
`= 2 - sqrt3 + sqrt3 - 1 - 8sqrt3`
`= 1 - 8sqrt3`