Question 1082704
Are you painting the ceiling? If the problem and/or the teacher didn't say, assume you are only painting the walls.
It's a rectangular room, 50 x 70, so you have
2*50*? = (the ? stands for the height of the walls, you need to decide)
2*70*? =
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Total = ? 
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For your reference, 30 or 40 for the height of the walls seems awfully high, you'd better double check.
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Now calculate all openings (windows and doors) that you don't have to paint:
(4*6*3)+(2*2*30)+(2*80/36) = Subtract this from your total for the walls
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NOTE!!: What is 80/36 for the doors?? Is it 80 x 36? Those would be HUGE doors. Are you mixing feet and inches?
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The rest of the problem you can solve yourself easily with a calculator, just get this part correctly first.