Answer:
Luis has 30 cards
Step-by-step explanation:
To solve this problem, we need to setup a system of equations.
If we call the amount of cards Juan has "J", Pedro "P", Maria "M" and Luis "L", we have that:
J + P + M + L = 62
P = J/3
M = J - 3
L = 2J
Substituting P, M and L in the first equation, we have:
J + J/3 + J - 3 + 2J = 62
13J/3 = 62 + 3
13J = 65 * 3
J = 15 cards
The amount of cards Luis has is:
L = 2J = 2 * 15 = 30 cards
It took him 2.6 hours to reach the top
Data;
- Uphill = 6km
- Downhill = 4km
- Total time taken = 8 hours
<h3>Speed</h3>
Let us calculate the speed during uphill and downhill
Since the time it took them to descend is twice the time it took them to ascend,
- Let x represent the time taken to ascend

From the calculation above, it took him 2.6 hours to reach the top.
Learn more on speed here;
brainly.com/question/4931057
Answer:
I think that the altimeter would read as '0'. Positive readings would show that she was above sea level and negative readings we would show that she was below sea level. I hope that this helps