SOLUTION: Write a convinceing argument: solve the problem below. Then write an argument that would convince a classmate that your answer is correct. John was hired by a painter to paint d

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Question 1078983: Write a convinceing argument: solve the problem below. Then write an argument that would convince a classmate that your answer is correct.
John was hired by a painter to paint doors. He was paied $10 for each door that he completed that did not need repainting by a painter. For each door that needed to be re-done, he was fined $5. On a bd day he painted 25 doors, but made a totaly of only $10. How many doors did he paint that did not need to be repainted?

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ =the number of doors he painted
that did not need to be repainted
+25+-+x+ = the number of doors that needed
to be repainted
---------------------
+10x+ is what he was paid for doors that
did not need repainting
+-5%2A%28+25+-+x+%29+ is what he was paid ( fined )
for doors needing repainting
-------------------------------------------
+10x+-+5%2A%28+25+-+x+%29+=+10+
+10x+-+125+%2B+5x+=+10+
+15x+=+135+
+x+=+9+
He painted 9 doors that did not need repainting
----------------------------------------------
check:
+10%2A9+-+5%2A%28+25+-+9+%29+=+10+
+90+-+5%2A16+=+10+
+90+-+80+=+10+
+90+=+90+
OK
You just need to explain +10x+-+5%2A%28+25+-+x+%29+=+10+