Tie the ribbon on the gift box and calculate the length of the ribbon at least. (length 15 cm, width 10 cm, height 8 cm, knot 20 cm)

Tie the ribbon on the gift box and calculate the length of the ribbon at least. (length 15 cm, width 10 cm, height 8 cm, knot 20 cm)

Think about the way to tie ribbons in a gift box. Each side must be wrapped with ribbons
Ribbon length = upper surface + lower surface + four sides + knot length
Ribbon length at least = 15x2 + 10x2 + 8x4 + 20 = 102CM

The gift box is 10cm in length and 6cm in width, and the knot part of the ribbon is 15cm in length. How much ribbon does it need to tie this box

2*10+2*6+4*2+15=55

A cuboid gift box 30 cm long, 20 cm wide and 15 cm high. Wrap a layer of wrapping paper around it. Here's one
Is rectangular wrapping paper 7 decimeters long and 4 decimeters wide enough?

Need wrapping paper = 2 * (30 * 20 + 20 * 15 + 30 * 15) = 2700 square centimeter = 27 square decimeter
Wrapping paper = 7 * 4 = 28 decimeters
Enough