How can angles be adjacent?
Adjacent angles are angles that are touching.
One way to think about it is this: say we have one angle. Then, we draw a line through the center of the angle, breaking it up into two smaller angles. However, the two are still touching.
In the example below, angle ABD is broken up into angles ABC and CBD, which are touching. This means that angles ABC and CBD are adjacent.
Another way to think about adjacent angles is to imagine two separate angles that are then put on top of each other to form one larger angle. In that case, we could say that the two smaller angles are adjacent.
In the example below, two angles, a yellow one and a green one, are placed on top of each other, so that they share a side and are adjacent.