What is the sum of two consecutive even numbers, the difference of whose squares is 84?

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Question:
What is the sum of two consecutive even numbers, the difference of whose squares is 84?

[A].

34

[B].

38

[C].

42

[D].

46

Answer: Option C

Explanation:

Let the numbers be x and x + 2.

Then, (x + 2)2 – x2 = 84

4x + 4 = 84

4x = 80

x = 20.

The required sum = x + (x + 2) = 2x + 2 = 42.