Let's assume that Kirby walks with a speed

for a time

, and that he runs with a speed

for a time

.
The total time available for Kirby to catch the train is:

and this must be equal to the sum of the two times t1 and t2:
The distance Kirby should cover is

and this should be equal to the sum of the distances covered by walking and by running:

So we have a system of 2 equations:


If we solve the system, we find:


So, Kirby needs to run at least for 8 minutes in order to catch the train.
Answer:
28.3
Step-by-step explanation:
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Answer:
f(-3)=4
Step-by-step explanation:
Substitute x=-3 into the function
f(-3)=(-3)^2-5
f(-3)=9-5
f(-3)=4
Answer: the number is 3
Step-by-step explanation:
Let the number be represented by x.
If 4 more than 4 times a certain number is the same as 4 more than the product of 3 and 4, it means that
4x + 4 = 4 + 3×4
4x + 4 = 4 + 12
4x + 4 = 16
Subtracting 4 from the left hand side and the right hand side of the equation, it becomes
4x + 4 - 4 = 16 - 4
4x = 12
Dividing the left hand side and the right hand side of the equation by 4, it becomes
x = 12/4 = 3