Sandy gets 3 marks for each correct sum and loses 2 marks for each incorrect sum. Sandy attempts 30 sums and obtains 60 marks. How many sums did Sandy get correct?
Answers:	A) 18	B) 20	C) 22	D) 24	E) 26

Rationale: "let x be the correct sums and ( 30 - x ) be the incorrect sums . 3 x - 2 ( 30 - x ) = 60 5 x = 120 x = 24 the answer is d ."
Answer: D