Percentage error in $\ A = \left( 2\frac{\mathrm{\Delta}a}{a} + 3\frac{\mathrm{\Delta}b}{b} + \frac{\mathrm{\Delta}c}{c} + \frac{1}{2}\frac{\mathrm{\Delta}d}{d} \right) \times 100\%$ $\ = 2 \times 1 + 3 \times 3 + 2 + \frac{1}{2} \times 2$ $= 2 + 9 + 2 + 1 = 14\%$