Answer:
x = 2
Step-by-step explanation:
CDEF is a parallelogram.
CE and FD are its diagonals.
Diagonals of a parallelogram bisects each other.
Therefore,
10x - 5 = 4x + 7
10x - 4x = 7 + 5
6x = 12
x = 12/6
x = 2
Thus, for x = 2, CDEF is a parallelogram.
