Convert the mixed number to an improper fraction:

\( 1\dfrac{1}{4} = \dfrac{5}{4} = 1.25 \).

\\( \\dfrac{11}{8} = 1.375 \\).

So \( \dfrac{11}{8} > 1\dfrac{1}{4} \).

The true statement is option 2.

Convert each fraction to twelfths:

• \( \dfrac{1}{2} = \dfrac{6}{12} \)
• \( \dfrac{2}{3} = \dfrac{8}{12} \)
• \( \dfrac{3}{4} = \dfrac{9}{12} \)
• \( \dfrac{5}{6} = \dfrac{10}{12} \)

From smallest to largest: \( \dfrac{6}{12} < \dfrac{8}{12} < \dfrac{9}{12} < \dfrac{10}{12} \).

So the correct order is 1/2,2/3,3/4,5/6.

Convert to improper fractions:

\( 2\dfrac{2}{5} = \dfrac{2 \times 5 + 2}{5} = \dfrac{12}{5} \)

\( 1\dfrac{3}{10} = \dfrac{1 \times 10 + 3}{10} = \dfrac{13}{10} \)

Add them:

\( \dfrac{12}{5} + \dfrac{13}{10} = \dfrac{24}{10} + \dfrac{13}{10} = \dfrac{37}{10} \).

Answer: \( \dfrac{37}{10} \).

Use a common denominator of 12:

\( \dfrac{3}{4} = \dfrac{9}{12},\quad \dfrac{5}{6} = \dfrac{10}{12} \).

So \( \dfrac{3}{4} + \dfrac{5}{6} = \dfrac{9}{12} + \dfrac{10}{12} = \dfrac{19}{12} \).

Answer: \( \dfrac{19}{12} \).

Multiply numerators and denominators:

\( \dfrac{5}{6} \times \dfrac{4}{9} = \dfrac{5 \times 4}{6 \times 9} = \dfrac{20}{54} \).

Simplify \( \dfrac{20}{54} \) by dividing top and bottom by 2:

\( \dfrac{20}{54} = \dfrac{10}{27} \).

Answer: \( \dfrac{10}{27} \).