SOLUTION: This problem is driving me nuts. ****** The math score on an exam can be written as: S=200 + 20R - 5W, where S is the score, R is the number of correct answers and W is the num

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: This problem is driving me nuts. ****** The math score on an exam can be written as: S=200 + 20R - 5W, where S is the score, R is the number of correct answers and W is the num      Log On


   

Question 85597This question is from textbook Plato Interactive Mathematics - Elementary Algebra
: This problem is driving me nuts.
******
The math score on an exam can be written as:
S=200 + 20R - 5W, where S is the score, R is the number of correct answers and W is the number of wrong answers.
Dana's score on the test was 525 and he answered 19 questions correctly. How many did he answer incorrectly?
*******
I know the answer to be 11, but I can't figure out how it was solved!!!!!!!!!!!!!
Please help.
 This question is from textbook Plato Interactive Mathematics - Elementary Algebra

Answer by dolly(163) About Me  (Show Source):
You can put this solution on YOUR website!
S=200 + 20R - 5W
Substituting S = 525 and R = 19,
525 = 200 + 20(19) - 5w
==> 525 - 200 = 380 - 5w
==> 325 = 380 - 5w
==> 5w + 325 = 380
==> 5w = 380 - 325
==> 5w = 55
==> w = 55/5
==> w = 11
No: of wrong answers = 11