please answer with detail on how you arrived to the conclusion The demand for good X has been estimated by Q X d - 3P X + 4P Y . Suppose that good X

please answer with detail on how you arrived to the conclusion 

The demand for good X has been estimated by QXd - 3PX + 4PY. Suppose that good X sells at $2 per unit and good Y sells for $1 per unit. Calculate the own price elasticity. A. -0.2 B. -0.3 C. -0.5 D. -0.6

Qxd = 12 - 3*2 + 4*1 = 10 dQx/dPx = -3Elasticity = (dQ/dP)*(P/Q)= -3*2/10= -0.6 Answer is D. -0.6