If a positive number when decreased by 3, is equal to 28 times the reciprocal of the number, then find the number.

Correct option is D

Given:

A positive number when decreased by 3, is equal to 28 times the reciprocal of the number

​Solution:​

Let the number be 'x'.

​$$x - 3 = 28 \times \frac{1}{x} \\ x^2 - 3x - 28 = 0 \\x^2 - 7x + 4x - 28 = 0 \\x(x - 7) + 4(x - 7) = 0 \\ (x + 4)(x - 7) = 0 \\ x = -4, 7$$

Then the number = 7 .