Calculate Surface Area: Finding Wrapping Paper for 20×30×70 cm Box

To solve this problem, we'll proceed as follows:

• Step 1: Identify the box dimensions and list them as length $l = 20 \, \text{cm}$, width $w = 30 \, \text{cm}$, and height $h = 70 \, \text{cm}$.
• Step 2: Use the surface area formula for a cuboid:
  $A = 2(lw + lh + wh)$
• Step 3: Calculate the individual areas:
  - Base: $lw = 20 \times 30 = 600 \, \text{cm}^2$
  - Front: $lh = 20 \times 70 = 1400 \, \text{cm}^2$
  - Side: $wh = 30 \times 70 = 2100 \, \text{cm}^2$
• Step 4: Compute the total surface area in cm²:
  $A = 2(600 + 1400 + 2100) = 2 \times 4100 = 8200 \, \text{cm}^2$
• Step 5: Convert to square meters (since $1 \, \text{m}^2 = 10,000 \, \text{cm}^2$):
  $8200 \, \text{cm}^2 = \frac{8200}{10000} = 0.82 \, \text{m}^2$

Thus, Ezequiel needs $0.82 \, \text{m}^2$ of wrapping paper.