Correct the following equation by interchanging the two signs:
5 × 15 ÷ 7 − 20 + 4 = 77
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → + and ÷
Each pair of signs is interchanged and the expression is worked out by the BODMAS order (division and multiplication before addition and subtraction), until one side comes to 77.
Option (1) − and + — \(5\times15\div7+20-4\): \(\frac{75}{7}\) is not a whole number, so the result cannot be 77.
Option (2) × and ÷ — \(5\div15\times7-20+4=\frac{7}{3}-16\), which is negative.
Option (3) + and ÷ — \(5\times15+7-20\div4=75+7-5=\) 77.
Option (4) + and × — \(5+15\div7-20\times4\), which is negative.