The Sean's number is x. Formulate the equation:
x * 5 : 2 = 30
5x = 30 * 2
5x = 60
x = 60 : 5
x = 12
Answer: the Sean's number is 12.
Let's first break it down to the time 8 people need for one wall. That would be 10 minutes, right? If one person would have to do it in stead of 8, you'd expect him to take 80 minutes.
To paint 7 walls, he would nee 7x80 = 560 minutes. 10 people would do that 10 times faster, ie., 56 minutes.
I know puzzles like these always have a mindtrick. Did I miss anything?? ;-)
<h3>
Answer: shaded region has area 107 square feet</h3>
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Work Shown:
A = area of larger rectangle
A = length*width = 9*15 = 135 square feet
B = area of smaller rectangle
B = length*width = 7*4 = 28 square feet
C = area of shaded region
C = difference in areas of A and B
C = A - B = 135 - 28 = 107 square feet
Answer: 
Step-by-step explanation: In some cases you must apply the exponent rule, simplify, or multiply them together to get your answer.