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The value of

\[ \begin{aligned} & 5\frac{1}{4} \div 3\frac{1}{2} \times \frac{5}{6} - \frac{3}{8} \\ & + \frac{2}{5} \div \frac{2}{15}\text{ of }1\frac{3}{5} - \frac{3}{4} \div \frac{5}{12} \end{aligned} \]

is:

  • A.\(\frac{9}{10}\)
  • B.\(\frac{3}{5}\)
  • C.\(\frac{19}{20}\)
  • D.\(\frac{39}{40}\)

Answer: C

The value is 19/20. Using BODMAS, 'of' is done first, then division and multiplication, then addition and subtraction. The first part is the division and multiplication:

\[ \frac{21}{4} \div \frac{7}{2} \times \frac{5}{6} \]

\[ = \frac{21}{4} \times \frac{2}{7} \times \frac{5}{6} \]

\[ = \frac{5}{4} \]

Next, the 'of' term and the divisions that follow it:

\[ \frac{2}{15} \text{ of } 1\frac{3}{5} \]

\[ = \frac{2}{15} \times \frac{8}{5} = \frac{16}{75} \]

\[ \frac{2}{5} \div \frac{16}{75} = \frac{15}{8} \]

\[ \frac{3}{4} \div \frac{5}{12} = \frac{9}{5} \]

Combining all the terms:

\[ \frac{5}{4} - \frac{3}{8} + \frac{15}{8} - \frac{9}{5} \]

\[ = \frac{11}{4} - \frac{9}{5} = \frac{19}{20} \]

The other options, 9/10, 3/5 and 39/40, come from a wrong order of operations.

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