Explanation:

Let’s walk through this:

- Equation: 15 - 4 + (8 × 6) ÷ 16 + 9 × 3 - 7 = 31

- First off, let’s solve it as is:

- (8 × 6) = 48

- 48 ÷ 16 = 3

- 15 - 4 = 11

- 9 × 3 = 27

- So, 11 + 3 + 27 - 7 = 34

- The sum is 34, not 31.

- Options involve switching numbers—let’s see which swap moves us from 34 to 31.

Option 1: Swap 6 and 16

- Now, it’s (8 × 16) ÷ 6

- (8 × 16) = 128; 128 ÷ 6 ˜ 21.33

- The rest: 15 - 4 + 21.33 + 27 - 7 ˜ 52.33

- Way off.

Option 2: Swap 4 and 6

- New equation: 15 - 6 + (8 × 4) ÷ 16 + 9 × 3 - 7

- (8 × 4) = 32; 32 ÷ 16 = 2

- 15 - 6 = 9

- 9 × 3 = 27

- 9 + 2 + 27 - 7 = 31

Option 3: Swap 8 and 16

- (16 × 6) ÷ 8 = 96 ÷ 8 = 12

- Rest: 15 - 4 = 11; 9 × 3 = 27

- 11 + 12 + 27 - 7 = 43

- Not right.

Option 4: Swap 4 and 3

- Now: 15 - 3 + (8 × 6) ÷ 16 + 9 × 4 - 7

- (8 × 6) ÷ 16 = 3

- 9 × 4 = 36

- 15 - 3 = 12

- 12 + 3 + 36 - 7 = 44

- Doesn’t work.

So, option 2 is the only swap that gets you to 31.

Correct Answer:

Option: 2, 4 and 6