At a meeting, 25 attendants used a pencil and 15 attendants used a pen. If exactly 20 attendants used only one of the two types of writing tools, how many attendants wrote with both types of writing tools?
Choose the correct choice
A) 10	B) 6	C) 7	D) 4	E) 14

Rationale: say x attendants wrote with both writing tools . ( 25 - x ) + ( 15 - x ) = 20 - - > x = 10 . answer : a .
Answer: A