During the sultanate period Diwan-i-arz was the department of________.

​$$\text{Simplify: } 4\left(\frac{7}{4}x^2 - 27x + 19\right) - 7(x^2 + 9x - 14)$$​​

The cost of 18 pens and 4 pencils is ₹200. If the cost of a pen decreases by Rs. 1 and the cost of a pencil increases by Rs. 3, then the cost of 19 pens and 3 pencils is Rs. 151. What is the original cost of 12 pens and 10 pencils?

​Simplify: $$3 \left( (\frac{7}{3}) x^2 - 27x + 14 \right) - 7 \left( x^2 + 8x - 11 \right)$$​​

Find the value of K, for which the quadratic equation x² + 4x + K = 0 has equal roots.