The answer is: 12 centimeters.
 The explanation is shown below:
 1. By definition, all four sides of the square are equal and the diagonals are equal too. 
 2. Keeping the information above on mind, you know that AC and BD are equal:
 
 3. Then, the length of BD is twice BE. So, you can calculate it as following:
 
 
 4. Therefore, the lenght of AC is:
 
 
        
             
        
        
        
Answer:
x = 19
Step-by-step explanation:
123°+3x = 180° 
3x = 180°-123°
3x = 57
x = 57/3
x = 19
The reason why we use 123° + 3x = 180° because both are adjacent angles. Adjacent angles add up to 180°
 
        
             
        
        
        
If the wall with 4 ft. of storage area can fit 6 sections of plant and the wall with 7 ft. Can fit 5, that means each section is 3 ft. because 7-4=3, so that extra section on the wall with 4 ft. You do this because there is one extra section on the wall with four. Knowing this, the wall with 7 ft. Would be the 7 ft. + 5 sections of 3 ft. So 7+(5x3) = 22. On the wall with 4 ft., do the same, 
4+(6x3) =22. Since they are equal and the walls are supposed to be equal, we can confirm this is the right answer