Respuesta :

Answer:

12.5

Step-by-step explanation:

In a rectangle, the two diagonals are equal length, so MK = JL = 2x + 9

Note MK = 2 * MN, so

2x + 9 = 2 * (3x + 1)

expand:

2x + 9 = 6x + 2

Solve:

9 - 2 = 6x - 2x

4x = 7

x = 7/4

MK = JL = 2x + 9 = 2 * 7/4 + 9 = 7/2 + 9 = 3.5 + 9 = 12.5

definitelygoat
12.5 is the answer. The explanation is because I did it already and I took a quiz on it