Step 1

First, we can split the angle into two parts by drawing a dotted line along the line BC. Here, we know that we can get ∠ÐABC by adding these two angles together.

Step 2

Let's measure the first part. We place the protractor on the vertex B and make sure that its base line is along BC as shown:

Step 3

By reading the inner scale, we can see that this angle is 180°.

Step 4

Next, we measure the second angle. We rotate the protractor and make sure that the base line is along AB as shown:

Step 5

By reading the outer scale, we can see that this angle is 45°.

Step 6

Hence, we can get ∠ÐABC by adding 180° with 45°.
Clearly, the answer is D.

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