<PRE><B>Question 969768</B>
You have a test score of 51.
 There were 20 problems on quiz.
 You received 5 points for each correct response and a 2 point deduction for each one incorrect. How many did you correct.
:
let x = no. of correct problem
then
(20-x) = no. of incorrect problems
:
5x - 2(20-x) = 51
5x - 40 + 2x = 51 
5x + 2x  = 51 + 40
7x = 91
x = 91/7
x = 13 correct problems
:
:
Check this, we know that he got 7 problems wrong
13 * 5 = 65
7 * -2 = -14
---------------
results: 51</PRE>