Sandy gets 3 marks for each correct sum and loses 2 marks for each incorrect sum. Sandy attempts 30 sums and obtains 50 marks. How many sums did Sandy get correct?
Choices
A) 20 B) 22 C) 24 D) 26 E) 28
Let x be the correct sums and (30-x) be the incorrect sums.   3x - 2(30-x) = 50   5x = 110   x = 22   The answer is 22.
<result>B</result>
Sandy gets 3 marks for each correct sum and loses 2 marks for each incorrect sum. Sandy attempts 30 sums and obtains 50 marks. How many sums did Sandy get correct?