Since ΔCDE is isosceles with base angles D and E equal then sides
CE = CD , hence
16x - 27 = 4x + 9 ( subtract 4x from both sides )
12x - 27 = 9 ( add 27 to both sides )
12x = 36 ( divide both sides by 12 )
x = 3
substitute x = 3 into the expressions for the sides
CD = (4 × 3 ) + 9 = 12 + 9 = 21
DE = (7 × 3 ) - 5 = 21 - 5 = 16
CE = (16 × 3 ) - 27 = 48 - 27 = 21
note that CE = CD
