Let n = minutes since 12:00 pm when Malory catches up to Dori.
Dori travels
(50 steps/min)*(n minutes) = 50n steps
Malory begins walking at 12:20 pm, so she walks for (n - 20) minutes. She travels
(90 steps/min)*(n - 20 min) = 90n - 1800 steps
Equate the steps traveled by Dori and Malory.
90n - 1800 = 50n
40n = 1800
n = 45 min
The time corresponding to n = 45 min is 12:45 pm
Answer: 12:45 pm
Answer:

For this case we know that
represent the radius,
the height and the rate given is:


And replacing we got:

And that represent 
Step-by-step explanation:
For a tank similar to a cylinder the volume is given by:

For this case we know that
represent the radius,
the height and the rate given is:

For this case we want to find the rate of change of the water level when h =6m so then we can derivate the formula for the volume and we got:

And solving for
we got:

We need to convert the rate given into m^3/min and we got:

And replacing we got:

And that represent 
Answer:
10+8x=y
Step-by-step explanation:
The 10$ is added on because it's a one time exchange and the 8 is multiplied by the x because for every hour you add 8$ to the price and y is the total price at the end depending on x.
As per the isosceles triangle theorem, if the two base angles are congruent then the legs are also congruent, so we must set the two legs equal to each other:
2z - 15 = 9
Add 15 to both sides:
15 - 15 = 0
15 + 9 = 24
Divide 2 from each side:
2z = 24
2z/2 = z
24/2 = 12
z = 12
Hence, the answer would be D: z = 12