For figure 18:
• Similarity Statement:
If two pairs of corresponding sides are in proportion, and the included angle of each pair is equal, then the two triangles they form are similar (SAS postulate).
• Scale factor (considering smaller figure is enlarged to the bigger one):

• To find x:


• To find missing sides:
AC = x + 7 = 3/5 + 7 = 7.6
CE = 12 - x = 11.4