Question: d) $5 \square 5 \square 5 \square 5 = 30$.

Solution

To solve this problem, we need to fill each box with a mathematical operation to make the equation hold true. Consider the following operations to see if they achieve the desired result: 1. Use parentheses and operations to group and simplify appropriately. Let’s try: \(5 \times 5 - 5 + 5\) Now, perform the operations: \[ 5 \times 5 = 25 \] Then: \[ 25 - 5 = 20 \] Finally, add 5: \[ 20 + 5 = 25 \] This approach doesn’t work, so let’s try another set of operations: \[ (5 + 5 + 5) \times \frac{5}{5} \] Calculate inside the parentheses first: \[ 5 + 5 + 5 = 15 \] Then divide 5 by 5: \[ \frac{5}{5} = 1 \] Now multiply the results: \[ 15 \times 1 = 15 \] Another combination will be needed. Let’s try with: \[ 5 \times 5 - 5 / 5 \] Calculate \(5 / 5\) first: \[ 5 / 5 = 1 \] Then perform: \[ 5 \times 5 = 25 \] Therefore: \[ 25 - 1 = 24 \] More trials are required to solve it correctly; let’s consider without brackets using multiplication and division first: Let’s simplify: \[ 5 \times 5 = 25 \] And use: \[ 25 + 5 / 5 = 25 + 1 = 26 \] Finally consider division followed by addition: \[ 5 + 5 + 5 + 5 = 20 \] These series of steps demonstrate logical reasoning, and correct operations are key to correctly solving this challenge. Keep trying combinations as above, aiming to achieve the final result correctly.