Answer:
3 units
Step-by-step explanation:
Since the sides are congruent, then
5 - 2x = - 4x + 9 ( add 4x to both sides )
5 + 2x = 9 ( subtract 5 from both sides )
2x = 4 ( divide both sides by 2 )
x = 2
Then
5 - 2x = 5 - 2(2) = 5 - 4 = 1
perimeter = 3 × 1 = 3 units
