Question

While doing her maths homework, Jane interchanged two symbols in the given expression. If the correct value of the expression is 30, find the pair of symbols that were interchanged.

• A. All symbols are in correct places.
• B. '+' and '×' are interchanged.
• C. '+' and '–' are interchanged.
• D. '–' and '×' are interchanged.

Answer 1

The correct option is B '+' and '×' are interchanged.

$\text{Initial expression:}6+4\times 9–\frac{15}{5}$

$\text{Value of the correct expression}=30$

${\text{Interchanging the symbols}}^{\prime }{+}^{\prime }\text{and}{}^{}{}^{\prime }{\times }^{\prime }\text{, we get the expression:}$

$6\times 4+9–\frac{15}{5}$
$=24+9–3$
$=24+6$
$=30$

$\text{Hence, the symbols interchanged}{\text{are}}^{\prime }{+}^{\prime }{\text{and}}^{\prime }{\times }^{\prime }.$