What is the length of side dg?

28 in.

19 in.

21 in.

12 in.

DG is 21.

Step-by-step explanation:

Clearly, we see a recurring pattern of multiplying by three.

Side AB is 5, and the shape on the left is 15.

Side BC is 6, and the shape on the right is 18.

This shows that we must do the same with DG. Multiply 7 by three.

DG = 21 in.

21 in

Step-by-step explanation:

Since the triangles are similar by SAS, we can find a pattern. The corresponding sides on the larger triangle are three times larger than the sides on the smaller triangle. So if AC is corresponding to side DG, and AC measures 7 in, then DG is 3*AC, or 3 * 7 which is 21 in.