If (20)² is subtracted from the square of a number, the answer so obtained is 4321. What is the number?
Choose the correct choice from the following answers
A) 68 B) 69 C) 70 D) 71 E) 72
x^2=4321+400= 
<gadget id="calculator">4321+400</gadget>
<output>4_721</output>
4721   4761=69*69   x=69   ANSWER:69
<result>B</result>
If (20)² is subtracted from the square of a number, the answer so obtained is 4321. What is the number?