It takes Max 1 minute and 45 seconds to run around a track once. It takes Max 3 minutes to walk one lap on the same track. If Max walks and runs around the track and completes 10 laps in 25 minutes, how many laps did he run?

4 laps running

Step-by-step explanation:

Les r be the number of laps he completed running an w the number of laps he walked. Also, lets write all in seconds, which can be a little easier than working with minutes.

Then, as it takes him 1:45 minutes by running, and we know that 1 minute is equal to 60 seconds, we can say it takes him 60+45=105 seconds to run a lap. Then, as it takes him 3 minutes to walk a lap we can say it takes him 3*60=180 seconds to walk a lap.

Thus, in total the minutes he needs if he runs r laps and walk w laps is:

time = 105 r + 180 w

As we know he did his laps in 25 minutes, which are equivalent to 25*60=1500 seconds:

105 r + 180 w = 1500 [equation 1]

We also know he completes 10 laps, which means that"

r + w = 10 [equation 2]

We can subtract w (or r) in both sides of equation 2 to get the value of r as a function of w:

r = 10 - w [equation 2']

Then we can plug equation 2' in equation 1 leaving all in terms of w:

105 r + 180 w = 1500

105 (10 - w) + 180 w = 1500

1050 - 105 w + 180 w = 1500

1050 + 75 w = 1500

If we subtract 1050 in both sides:

75 w = 1500 - 1050

75 w = 450

Dividing both sides by 75 we get the value of w:

w = 450/75

w = 6

So, he walked 6 laps. Then, he must have run the remaining 4 laps.