A line makes an angle of 30˚ from the x-axis in an anti-clockwise direction. Find the angle that this line will make with y-axis in anti-clockwise direction:

Now, we know that the coordinate axes make 90˚ with each other.

So, the angle made by y-axis = 90˚ - 30˚

Angle made by the line and y-axis in anti-clockwise direction = 60˚