An unpainted wall with a total area of 100 square feet needed to be pa

We can PLUG IN THE ANSWERS, which represent the area painted by all 3 workers.
Start with the largest value among the answer choices -- 60 square feet -- to determine the maximum area that can be painted by all 3 workers.
When the correct answer is plugged in, the total area painted = 100 square feet

Case 1: 60 square feet painted by all 3 workers
Of the 70 square feet painted by Jamaica, the area that receives 3 coats of paint = 60, implying that the area painted by Jamaica that could receive 1 coat of paint = 70-60 = 10
Of the 80 square feet painted by Bryan, the area that receives 3 coats of paint = 60, implying that the area painted by Bryan that could receive 1 coat of paint = 80-60 = 20
Total area that receives paint = sum of the blue values above = 60+10+20 = 90
The total area painted is too small.
Since it is not possible that q=60, eliminate B and E.

Among the remaining answer choices, the next largest option = 55 square feet

Case 2: 55 square feet painted by all 3 workers
Of the 60 square feet painted by Nelson, the area that receives 3 coats of paint = 55, implying that the area painted by Nelson that could receive 1 coat of paint = 60-55 = 5
Of the 70 square feet painted by Jamaica, the area that receives 3 coats of paint = 55, implying that the area painted by Jamaica that could receive 1 coat of paint = 70-55 = 15
Of the 80 square feet painted by Bryan, the area that receives 3 coats of paint = 55, implying that the area painted by Bryan that could receive 1 coat of paint = 80-55 = 25
Total area that receives paint = sum of the blue values above = 55+5+15+25 = 100
Success!
Since it is possible that q=55, eliminate A and C.