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 70, then how long is the base of isosceles triangle?	Choose the correct choice from the following options.
A) 15  B) 20  C) 25  D) 30  E) 35

Rationale: "the base of the isosceles triangle is 70 - 20 - 20 = 30 units the answer is d ."
Answer: D