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 side lengths of the longest side measures 6.2 cm?

Let a = longest side       (Establishing labels)
let b = shortest side
let c = third side

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

P = a + b + c
P = 6.2 + 3.1 + c        (Fill in given info in equation)

P = 9.3 + c                (Simplify)

14.5 = 9.3 + c           (Simplify)

c = 14.5 - 9.3           (Solve)
c = 5.2

Hope this made sense!