Example 1: This graph shows how the distance Marcela runs depends on the number of track practices she attends.

Example 2: This graph shows how the cost of a corporate team-building event depends on the number of attendees.

Practices, x	Distance in miles, y	yx = k
1	2	21 = ?
2	4	42 = ?
3	6	63 = ?
4	8	84 = ?
5	10	105 = ?

What is the constant of proportionality, k?

Write your answer as a decimal or integer.

miles per practice

Number of attendees, x	Cost in dollars, y	yx = k
2	1	12 = ?
4	2	24 = ?
6	3	36 = ?
8	4	48 = ?
10	5	510 = ?

What is the constant of proportionality, k?

$ per attendee