-5sqrt12 - 6sqrt27 - 3sqrt48

Guessing that you are taking 9th grade math, here is how you do it:
for simplifying radicals find perfect square factors of what's under, and multiply what's left by its square root
ex. Sqrt50
50=25 times 2
sqrt50=5sqrt2
1.-5sqrt12
12=4 times 3
-5sqrt12=-10sqrt3
2.6sqrt27
27=3 times 9
6sqrt27=18sqrt3
3.3sqrt48
48=16 times 3
3sqrt48=12sqrt3
-10sqrt3 + -18sqrt3 + -12sqrt3
with like terms we can now subtract to
-40sqrt3

it's important to know that mathwiz is using the rule ./(a.b) = (./a) x (./b)

i.e. . /50 = ./(25x2) = (./25) x (./2)
= 5./2

(where I'm using ./ to mean sqrt)

Correct g13544055