A rectangular cardboard cut shadow according to the figure, just can make a cylinder, calculate the surface area of the cylinder I drew the wrong circle, which is the same size

A rectangular cardboard cut shadow according to the figure, just can make a cylinder, calculate the surface area of the cylinder I drew the wrong circle, which is the same size

As shown in the figure, let the length of the rectangle be x and the diameter of the circle be r
x=πR
x+2R=41.12
If you solve the equation, you get
x=25.12
R=8
Surface area of cylinder = 2 * π (R / 2)? + X * r = 301.44cm?

This is an expanded view of a cuboid carton. What is the surface area and volume of the carton? (unit: cm)

The shape of the cuboid is as follows: the surface area of the carton is (30 × 20 + 30 × 5 + 20 × 5) × 2-30 × 20 = (600 + 150 + 100) × 2-30 × 20 = 850 × 2-30 × 20 = 1700-600 = 1100 (square centimeter) and the volume is: 30 × 20 × 5 = 600 × 5 = 3000 (cubic centimeter). A: the surface area of the carton is 1100 square centimeter and the volume is 3000 cubic centimeter

The figure below is an expanded view of a cuboid. Find the surface area and volume of the cuboid

Height = width = 15 / 3 = 5
Length = 17-5 × 2 = 7
Surface area: 17 × 5 + 15 × 7 = 190 (M2 * *)
Volume: 7 × 5 × 5 = 175 (cubic * *)
I have a problem with this answer. See the comments below. The answer is not modified. Let's put it here for discussion