$\frac{180 \times 15 - 12 \times 20}{140 \times 8 + 2 \times 55} = ?$

Choose the incorrect relation$(s)$ from the following:
$(i)$ $\sqrt{6}+\sqrt{2}=\sqrt{5}+\sqrt{3}$
$(ii)$ $\sqrt{6}+\sqrt{2}<\sqrt{5}+\sqrt{3}$
$(iii)$ $\sqrt{6}+\sqrt{2}>\sqrt{5}+\sqrt{3}$

If $\frac{\sqrt{3+x}+\sqrt{3-x}}{\sqrt{3+x}-\sqrt{3-x}}=2,$ then $x$ is equal to

What is the value of $(2.3+1.7)^{2}-(2.3-1.7)^{2} ?$

What will come in the place of the question mark $(?)$ in the following expression?
$\sqrt{15^{2} \times 12 \div 9 - 125 + 21} = ?$

$\frac{3}{48}$ is what part of $\frac{1}{12}$?