statistics – Distribution of X

$X_1+X_2$ and $X_1-X_2 $ are $i.i.d$. $N(1,4)$ What is the distribution of $X = (X_1,X_2)^T$?
I know $i.i.d.$ is an independent and identically distributed random variable but I don’t know how to use it to solve this problem that contains a column vector.