Answer:
Use a line graph with multiple lines.
Step-by-step explanation:
Since line graphs show data over time, and you have multiple people, this is a perfect choice. Put the days or however amount of time on the x axis, and the gallons or a different water amount on the y-axis. Color-code the lines to each family member.
Answer:
27
Step-by-step explanation:
Answer:
80 members
Step-by-step explanation:
Let the band members be= b and the chorale members= c
Then, according to question, b=c+30 and 
⇒
⇒
⇒
⇒
Now, substituting the value of b=c+30, we get
⇒
⇒
⇒
⇒
Therefore, 

Therefore, there are 80 members in the band.
It is called parallel lines when there is two line that never intersect