| Question | If the following interchanges are made in signs and numbers, which equation would be correct? Interchanges: Signs: ÷ and – Numbers: 15 and 5 | |
| Type | multiple_choice | |
| Option | 4 × 30 – 15 ÷ 5 + 12 = 21 | correct |
| Option | 12 × 30 – 15 ÷ 5 + 4 = 37 | incorrect |
| Option | 4 × 30 – 15 ÷ 5 + 12 = 27 | incorrect |
| Option | 4 × 30 – 5 ÷ 15 + 14 = 21 | incorrect |
| Solution | Given 4 × 30 – 15 ÷ 5 + 12 = 21 Interchanging ÷ & – and 15 &5 ∴ 4 × 30÷ 5 –15+12 = 21 ➙ 4 × 6 –15+12 = 21 ➙ 24-15+12 = 21 ➙ 21 = 21 (proved) | |
