A)18(√3-2√2)+15(2√3-3√2)-7(3√3-√2)=
18(√3-2√2)+15(2√3-3√2)-7(3√3-√2)=
18√3-36√2+30√3-45√2-21√3+7√2=
27√3-74√2
b)5(4√3-3√5)-7(2√3+4√5)+2(3√3+6√5)=
20√3-15√5-14√3-28√5+6√3+12√5=
12√3-31√5
c)(18√2-24√3):6+2(4√3-3√2)-(30√3+15√2):5=
3√2-4√3+8√3-6√2-6√3-3√2=
-6√2-2√3=-2(3√2+√3)