Calculate the following using Brahmagupta's laws:
(i) $(-12) \times 5$
(ii) $(-8) \times (-7)$
(iii) $0 - (-14)$
(iv) $(-20) \div 4$

(i) Given, (-12) × 5

By Brahmagupta's law, the product of a debt and a fortune is a debt.

⇒ (-12) × 5

⇒ -60.

Hence, (-12) × 5 = -60.

(ii) Given, (-8) × (-7)

By Brahmagupta's law, the product of two debts is a fortune.

⇒ (-8) × (-7)

⇒ +56.

Hence, (-8) × (-7) = 56.

(iii) Given, 0 - (-14)

Subtracting a negative number is the same as adding its positive value.

⇒ 0 - (-14)

⇒ 0 + 14

⇒ 14.

Hence, 0 - (-14) = 14.

(iv) Given, (-20) ÷ 4

The quotient of a debt and a fortune is a debt.

⇒ (-20) ÷ 4

⇒ $\dfrac{-20}{4}$

⇒ -5.

Hence, (-20) ÷ 4 = -5.