3*squareroot(3) is the answer
2*sqrt(12) = 2*sqrt(4*3) = 2*sqrt(4)*sqrt(3) = 2*2*sqrt(3) = 4*sqrt(3)
sqrt(27) = sqrt(9*3) = sqrt(9)*sqrt(3) = 3*sqrt(3)
sqrt(48) = sqrt(16*3) = sqrt(16)*sqrt(3) = 4*sqrt(3)
therefore,
4*sqrt(3) + 3*sqrt(3) - 4*sqrt(3)
3*sqrt(3) + (4*sqrt(3)-4*sqrt(3))
3*sqrt(3)
