1.  Thrice the square of a natural number decreased by 4 times the number is equal to 50 more than the number. The number is ?
A. 5
B. 4
C. 7
D. 6

Answer: Option A

Explanation:

Let the number be x. Then,

- 4x = x + 50

- 5x - 50 = 0

(3x + 10)(x - 5) = 0

x = 5