Hello!
She placed 6 ribbons
2 at the ends and 5 every 3 meters
        
             
        
        
        
Students in 2014 = (100% + 33%) × 2,300
students in 2014 = 133% × 2,300
students in 2014 = 133/100 × 2,300
students in 2014 = 3,059
There are 3,059 students in 2014
        
             
        
        
        
The answer is 573
S is the three digit number.
h - a number of hundreds
t - a number of tens
o - a number of ones
S = 100h + 10t + o
<span>The last two digits add to make ten: t + o = 10
</span><span>The first and last digits add to make eight: h + o = 8
</span><span>The first two digits add to make twelve: h + t = 12
</span>t + o = 10          ⇒ o = 10 - t
h + o = 8           ⇒ o = 8 - h
_______
10 - t = 8 - h
h + t = 12          ⇒ h = 12 - t
_______
10 - t = 8 - (12 - t)
10 - t = 8 - 12 + t
10 - t = -4 + t
10 + 4 = t + t
2t = 14
t = 14/2 = 7
______
h = 12 - t = 12 - 7 = 5
______
o = 8 - h = 8 - 5 = 3
S =  100h + 10t + o
h = 5
t = 7
o = 3
S = 100*5 + 10*7 + 3
   = 500 + 70 + 3
   = 573
        
             
        
        
        
Add 7 and 2 you will get 9, therefore the length of the post is 9.
        
                    
             
        
        
        
I hope this helps you 
2x+8= -7-3x
5x= -15
x= -3