The perimeter of an equilateral triangle is 60. If one of the sides of the equilateral triangle is the side of an isosceles triangle of perimeter 50, then how long is the base of isosceles triangle?  Choices
A) 5
B) 10
C) 15
D) 20
E) 25
The base of the isosceles triangle is 50-20-20= 
<gadget id="calculator">50-20-20</gadget>
<output>10</output>
10 units   The answer is 10.
<result>B</result>
The perimeter of an equilateral triangle is 60. If one of the sides of the equilateral triangle is the side of an isosceles triangle of perimeter 50, then how long is the base of isosceles triangle?