The perimeter of a scalene triangle is 14.5 cm. the longest side is twice that of the shortest side. which equation can be used to find the side lengths if the longest side measures 6.2cm?

Let a = longest side      
let b = shortest side
let c = third side

P = 14.5                     
a = 6.2
b = 1/2(a)

P = a + b + c
P = 6.2 + 3.1 + c        

P = 9.3 + c                

14.5 = 9.3 + c           
c = 14.5 - 9.3          
c = 5.2

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