A community swimming pool starts with 250 gallons of water. Julian starts filling the pool at a rate of 500 gallons per hour.

What’s the initial number of gallons in the pool? That’s the same as the vertical intercept, or where the line crosses the vertical axis.
t
g
0
1
2
3
4
5
6
7
8
9
10
0
250
500
750
1,000
1,250
1,500
1,750
2,000
2,250
2,500
Time in hours
Gallons of water in the pool
Rate of change: 500
Initial amount: