Aptitude Hack#139(12-07-19)

Question;

Find a positive number which when increased by 16 is equal to 80 times the reciprocal of the number
A)  20
B)  -4
C) -10
D)   4

Answer: D) 4.

Explanation: 
Let the number be x.
Then x + 16 = 80 * (1/x)
x２ + 16x – 80 = 0
x２ + 20x – 4x – 80 =0
(x + 20) (x -4)
Therefore x = 4