∠yxz = 180 - (45 + 15) = 180 - 60 = 120o Using sine rule \(\frac{x}{sinx}=\frac{7}{sinz}\) \(\frac{x}{sin 120}=\frac{7}{sin 45}\) x = \(\frac{7 sin 120}{sin45}\) x = \(\frac{7sin(180-120)}{sin 45}\) x = \(\frac{7 sin 60}{sin 45}=\left(7\left(\frac{\sqrt{3}}{2}\right)\div \frac{1}{\sqrt{2}}\right)\) x = \(\left(7\left(\frac{\sqrt{3}}{2}\right)\div \frac{1}{\sqrt{2}}\right)\) x = 7\(\left(\frac{\sqrt{6}}{2}\right)\)