Answer:
Step-by-step explanation: <u>Speed</u> is distance an object travelled per unit time.
It is represented by letter v and can assume various units.
1) 

v = 18 miles per hour
Her average speed is 18 mph.
2) Rearraging formula for distance:
d = v.t
d = 70 * 4
d = 280 miles
You would travel 280 miles.
3) 

v = 52.5 mph
My average speed is 52.5 mph.
4) Rearranging formula to determine time:


t = 2.34 hours
It will take 2 hours and half to arrive in Leeds. So, we will be expected to arrive at 12:04.
5) The unit change but the way of calculating time is the same.

t = 500 s
or t = 8.34 minutes
It will take, for an athlete to run 2000m, 8.34 minutes.
6) a) All units must match, so for a speed in mph:
45 minutes is 0.75 hours. Total time is 8.75 hours.

v = 560 mph
The average speed is 560 mph.
b) 

t = 6.67 hours
Sam will take 6.67 hours to covered the distance.
X=-3
because
-4x=21-9
-4x= 12 divide both sides
x=-3
Slope-intercept form: y = mx + b
m = the slope
b = y-intercept.
In this problem,
m = 3/5
b = ?
So far y = 3/5x + b
Let's plug the point (-3, -1) into our slope equation.
-1 = 3/5(-3) + b
Simplify the right side.
-1 = -9/5 + b
Add 9/5 to both sides.
4/5 = b
The equation is: y = 3/5x + 4/5
Answer choice A is correct.