Which two signs should be interchanged to make the equation mathematically correct?
120 + 18 × 40 – 10 ÷ 20 = 172
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. ÷ and –.
Given equation: 120 + 18 × 40 – 10 ÷ 20 = 172
Option 1: – and +
After interchanging the expression becomes:
= 120 – 18 × 40 + 10 ÷ 20 = 172
= -599.5 is not equal to 172.
Option 2: ÷ and –
After interchanging the expression becomes:
= 120 + 18 × 40 ÷ 10 – 20 = 172
= 120 + 18 × 4 – 20
= 120 + 72 – 20
= 172 is equal to 172.
As we have found our answer, there is no need to check further options.
Hence, ÷ and – is the correct answer.