The Perimeter of a Triangle Is $66 \mathrm{~cm}$ the Triangle Is Isosceles Now, but If Its Base

Multiple Choice

The perimeter of a triangle is $66 \mathrm{~cm}$ . The triangle is isosceles now, but if its base were lengthened by $6 \mathrm{~cm}$ and each leg were shortened by $3 \mathrm{~cm}$ , it would be equilateral. Find the length of the base of the original triangle.

A) $22 \mathrm{~cm}$
B) $25 \mathrm{~cm}$
C) $16 \mathrm{~cm}$
D) $15 \mathrm{~cm}$