Posted by matt on Tuesday, April 9, 2013 at 3:03pm.
A math contest consists of ten problems.Three points are given for each correct answer. One point is deducted for each incorrect answer. Andy answers all the problems and scores 18 points. How many correct answers does he have?

math  rbowh, Tuesday, April 9, 2013 at 3:17pm
x = number of answers
y = number of incorrect answers
3 x  y = 18
x + y = 10
add the two equations and solve for x
check your answer 
math  matt, Tuesday, April 9, 2013 at 3:20pm
How do you that rbowh? I am really bad at this.(step by step please)

math  Ms. Sue, Tuesday, April 9, 2013 at 3:28pm
What part of the explanation don't you understand?

math  matt, Tuesday, April 9, 2013 at 3:33pm
How to solve for x.(i am terrible at this)

math  rbowh, Tuesday, April 9, 2013 at 3:34pm
what did you get when you added the two equations?

math  matt, Tuesday, April 9, 2013 at 3:35pm
That is what I don't get.Please can you show me how to do it.

math  rbowh, Tuesday, April 9, 2013 at 3:36pm
by the way, x represents number of correct answers  I left that out initially

math  matt, Tuesday, April 9, 2013 at 3:38pm
Step by step is what I meant.

math  rbowh, Tuesday, April 9, 2013 at 3:42pm
(3x  y) + (x + y) = 18 + 10
4 x = 28
x = ? 
math  matt, Tuesday, April 9, 2013 at 3:43pm
Thank you very kind sir/ma'am you were a big help.

math  rbowh, Tuesday, April 9, 2013 at 3:46pm
You're welcome Matt.

math  ANIKA, Sunday, February 14, 2016 at 3:00am
3*0=0
3*1=3
3*2=6
3*3=9
3*4=12
3*5=15
3*6=18 
math  sergio, Monday, October 3, 2016 at 6:13am
3x+y=18
x+y=10
x=4