First the person with a flashlight and one of his friends cross the bridge. After that same person with a flashlight comes back and leads another friend to the other side. Finally he comes back again and leads the last of them.
Number of times that he will have to cross the bridge is 5 ( five ).
15
3 x 5 or 5 x 3
35
5 x 7 or 7 x 5
So the answer is 5
W - a width
3w - a length
27 ft² - an area
Therefore:
w · 3w = 27
3w² = 27 |:3
w² = 9 → w = √9 → w = 3
3w = 3 · 3 = 9
width = 3
length = 9
The perimeter:
P = 2 · width + 2 · length
P = 2 · 3 + 2 · 9 = 6 + 18 = 24 ft.
The answer is C. -0.25; the rate at which Martin's distance from the finish line changes per minute