Question 14039:  the first side of a triangle is 5 more than 3 times the third side. the second side is 5 less than twice the third side. if the perimeter is 60cm, how long is each side? 
 Answer by bam878s(77)      (Show Source): 
You can  put this solution on YOUR website! Let x=length of third side, y=length of first side, and z=length of second side. 
From the problem, we know  
1. y=lenght of the first side= 5 more than 3 times the third side = 3x+5 
2. z=length of the second side= 5 less than 2 times the third side = 2x-5 
3. x=length of the third side. 
4. The sum of these lengths, by definition is the perimeter. 
We have, 
perimeter=60= x + (3x+5) + (2x-5). 
solve for x. 
60=x+3x+5+2x-5 
60=6x+5-5 
60=6x 
10=x
 
Now plug x back into your other equations to solve for the other sides. 
y=length of first side=3x+5 = 3(10)+5 = 30+5 = 35 
z=length of second side = 2x-5 = 2(10)-5= 20-5 = 15.
 
so 
x=10 
y=35 
z=15. 
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