Question 18

Which two signs should be interchanged in the following equation to make it correct?
$$5 \times 15 \div 7 - 20 + 4 = 77$$

Solution

By trial and error method,

Option A

$$5\times15\div7+20-4=77$$

$$\frac{5\times15}{7}+20-4=77$$

$$\frac{75}{7}+20-4=77$$

75 is not divisible by 7 so we get a decimal number after solving which is not possible

Option B

$$5\times15+7-20\div4=77$$

$$5\times15+7-5=77$$

$$75+7-5=77$$

$$77=77$$

Hence, the correct answer is Option B

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Which two signs should be interchanged in the following equation to make it correct?$$5 \times 15 \div 7 - 20 + 4 = 77$$