The area of rhombus ABCD is 72 square units. EC is equal to 8 units and DB is equal to x minus 1 What is the value of x ?

The diagonals of a rhombus bisect each other, so if EC = 8, the full diagonal AC is 16. The area is half the product of the diagonals: 72 = ½ × 16 × (x − 1). Solving gives x − 1 = 9, so x = 10. The correct choice is 10.

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