In the diagram above, BD = 8, AB = 6, and ED = 5. What is the length of AE?
A. 3
B. 4
C. 5
D. 7
E. 10

(C) Use this link for a flash video web page explanation: http://www.800score.com/explanations/GMAT_MATH_T1_Q6_Easy.html
We are given that BD = 8, AB = 6, and ED = 5. Let's break this problem down into a few steps.

1) Since triangle ABD is a right triangle where lengths of the two shorter sides are in the ratio of 4 to 3, the triangle must be a 3-4-5 right triangle (a common right-triangle type).

2) We can find the length of AD.
AB = 3 × 2 = 6
BD = 4 × 2 = 8
Therefore, AD = 5 × 2 = 10.

3) Since AE + ED = AD, AE + 5 = 10

4) AE must equal 5.

The correct answer is choice (C).
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I used this formula. Area of a triganle will be A = (1/2)bh. And we know BD = 8, AB = 6, ED = 5.
Therefore Area = 1/2 × 8 × 6 = 24.
We need the parameter of the diagram which is P = BD + AB + ED + AE, AE is unknown.
P = 8 + 6 + 5 + AE.
However we know the area of the entire diagram. From adding the
parimteter p = 8 + 6 + 5 = 19
Subtracting parimeter from Area 24 – 19 = 5 this will represent AE. Therefore, AE = 5.

I know this can be represented in a better way or correct way..
Thank you...

That is NOT correct.
A perimeter is measured in units, while an area is measured in square units. You CANNOT add or subtract values that have different units. A perimeter does NOT equal to an area.

That's exactly what we did. We calculated the hypotenuse of ABD using the property of the 3-4-5 right triangle (You can use the Pythagorean theorem instead). It equals 10. Then we subtracted ED, which equals 5, and calculated the length of AE: 10 – 5 = 5.