The sum of the edges of a rectangular parallelepiped is 80m, which is equal to the lengths of its sides if one edge is 20cm

The sum of the edges of a rectangular parallelepiped is 80m, which is equal to the lengths of its sides if one edge is 20cm larger than the other and 3cm less than the third.

Let the length of the middle edge be x, then the length of the smaller edge is x – 20, and the length of the larger edge is x + 3.
The sum of the lengths of the three edges is x + (x – 20) + (x + 3). By condition, it is equal to 80 cm, therefore,
x + x – 20 + x + 3 = 80, which is equivalent to 3x – 17 = 80, or 3x = 97, x = 32 1/3 cm.
This means that the length of the second rib is 32 1/3 – 20 = 12 1/3 cm, and the length of the third rib is 32 1/3 + 3 = 35 1/3 cm.
Answer: 32 1/3 cm; 12 1/3 cm and 35 1/3 cm.