SOLUTION: Mr Brown gave a test with 30 questions worth 100 points. If some of the questions were worth three points and the rest worth 5 points, how many questions of each value did he have?

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Question 858120: Mr Brown gave a test with 30 questions worth 100 points. If some of the questions were worth three points and the rest worth 5 points, how many questions of each value did he have?
Answer by ben720(159) About Me  (Show Source):
You can put this solution on YOUR website!
As the only types of questions were 3 points or 5 points, if you
Let X = how many 3-pointers there are
then the rest, or 30-x, must be 5-pointers.
The equation is 3*(number of 3-pointers) + 5*(number of 5-pointers) = total points.
Substitute
3x+%2B+5%2830-x%29+=+100
Distribute
3x+%2B+150+-+5x+=+100
Combine like terms
-2x+%2B+150+=+100
Add 2x to both sides
150+=+100+%2B+2x
Subtract 100 from both sides
50+=+2x
Divide both sides by 2
25+=+x
3pointers = x, 5-pointers = 30-x
There were 25 questions worth 3 points and 5 worth 5 points.