Answer:
the answer is x=15 cm
Explanation:
here the above given figure is a rectangle ABCD with diagonals AC and BD measuring AC= (x+10)cm and BD=(3x-20) cm
Now,
AC=BD
or, 3x-20 = x+10 [ diagonals of a rectangle are equal]
or, 2x = 30
or, x= 15 cm
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