Robert needs to cut four shelves from a board that is 2.5 meters long the second shelf 18 centimeters longer than twice the length of the first shelf the thrid shelf is 12 cm shorter than the the first shelf the remaining shelf is 4 cm longer than the first shelf if robert must use the entire 2.5 meter board for the shelves egat is the length of the second shelf in cm

Total length of the board = 2.5 meters
                                       =  (2.5 * 100) cm
                                       = 250 cm
Let us assume the length of the first shelf = x
Then
Length of the second shelf = 2x + 18
Length of the third shelf = x - 12
Length of the fourth shelf = x + 4
Now we can easily get the equation as
x + 2x + 18 + x - 12 + x + 4 = 250
5x + 10 = 250
5x = 250 - 10
5x = 240
x = 240/5
  = 48 cm
length of the second shelf = 2x + 18
                                          = 2(48) + 18
                                           = 96 + 18
                                         = 114 cm
So the length of the second shelf is 114 cm.