Answer:
t = 6 s
Step-by-step explanation:
Given that,
Sherry is driving 390 miles to visit The gateway arch in St. Louis.
She drives at an average rate of 65 miles per hour.
We need to find the amount of time it will take Sherry to get to the arch. Let the time is t.
Speed = distance/time

Hence, it will take 6 hours to get to the arch.
"c" is the hypotenuse of the largest triangle, and "a" is that triangle's shortest side. Thus the ratio is
... (longest side)/(shortest side)
Since all the triangles in the figure are similar, to complete the proportion, you need to recognize the triangle that "a" is the longest side of, then find the shortest side of that triangle.
"a" is the longest side (hypotenuse) of the smallest triangle. The shortest side of that triangle is "r". So, your proportion is ...
... c/a = a/r
The appropriate choice is the 2nd one, ...
... r
6 / (2/5) = 15
It should take the nail 15 minutes to crawl 6 meters.
(1) The train travels 4 miles per gallon.
(2) The slope of the graph is 
Explanation:
(1) The miles that train travels per gallon is given by

Dividing, we have,

Thus, the train travels 4 miles per gallon.
(2) To determine the slope, let us consider two points from the graph.
The coordinates are
and 
Thus, substituting the coordinates in the slope formula, we get,

Simplifying, we have,

Thus, the slope of the graph is 
If the chalkboard is just rectangular we can just use:
(2 x L) + (2 x W)
or
L+L+W+W
L= Length
W= Width