Calculați :

[tex] {6}^{30} \div ( {2}^{27} \times {3}^{28} ) = [/tex]
[tex]( {a}^{5} \times {a}^{2} )^{3} \div ( {a}^{4})^{5} [/tex]
[tex]x \times ( {x}^{5} \div {x}^{4} ) ^{2} [/tex]