Perimeter of an equilateral and isosceles is 45 and 40 respectively. At least one of the sides of isosceles is equal to the equilateral. What's the base of isosceles triangle? Pick one
A) 7 B) 8 C) 9 D) 10 E) 11

Rationale: 10 units as other 2 sides will be 15,15 units . answer : d
Answer: D