Answer:
see explanation
Step-by-step explanation:
Given AB ≅ BC, then
AB = BC = x + 6 , and
AC = AB + BC ← substitute values
3x - 31 = x + 6 + x + 6, that is
3x - 31 = 2x + 12 ( subtract 2x from both sides )
x - 31 = 12 ( add 31 to both sides )
x = 43
Hence
AB = BC = x + 6 = 43 + 6 = 49
AC = 3x - 31 =(3 × 43) - 31 = 129 - 31 = 98
