If x = 3t, y = 1/2 (t + 1), then the value of t for which x = 2y is?

Answer: Option B

$$\begin{array}{rl}& x=3t......(i)\\ & y=\frac{1}{2}\left(t+1\right)\\ & x=2y\\ & \Rightarrow x=2\times \frac{1}{2}\left(t+1\right)\\ & \Rightarrow x=t+1......(ii)\\ & \therefore 3t=t+1\\ & \left(\text{From equation (i) and (ii)}\right)\\ & \Rightarrow 2t=1\\ & \Rightarrow t=\frac{1}{2}\end{array}$$