15.
Find the perimeter of the smaller figure given that the two figures are similar.

Let: s1 = one of the sides of the larger figure
: s2 = one of the sides of the smaller figure
: p1 = perimeter of the larger figure
: p2 = perimeter of the smaller figure
s1/s2 = p1/p2. The ratio of the corresponding sides is the same as the perimeter of the figures.
p1 = 30 + 30 + 35 + 5 + 10 = 110

s1 = 30 and s2 = 18
p1 = 110 and p2 is ?

s1/s2 = p1/p2
30/18 = 110/?
Crisscross 30*? = 18*110

30*? = 1980
Divide both side by 30 30*?/30 = 1980/30
? = 66