Keep in mind that the positive directions of the two axis are: upwards for the y axis and rightwards for the x axis.
So, translating a point 6 units up means to go 6 units along the positive direction on the y axis. For this reason, the new y coordinate will be 6 units more than the old one.
Similarly, going 3 units left means to decrease by 3 the x coordinate, because we're following the negative direction.
So, to recap, this transformation maps
This means that the two points become
