6 minutes and a few seconds
The graph of P = 35 - 1/4Q is a straight line passing through points (0, 35) and (140, 0)
I believe it would be any number that is within the darkest shaded area. (-4,1) seems like it would be correct.
Answer:
x = 37.8
y=39.6
Use similar triangles. These used to be tricky back in the day.