Answer:
The fraction of the total distance to her uncle's house that was traveled on Sunday is 1/7
Step-by-step explanation:
Let the total distance from Madison house to her uncle is 1 unit
She travels 5/7th of the total distance on Saturday
Remaining distance = 
She travels 1/2 of the remaining distance on Sunday.
Hence, the fraction of the total distance to her uncle's house that was traveled on Sunday is 1/2 * 2/7 = 1/7
After using the slope formula your answer would be 5/0.1 but when simplifying your answer is 50
After 18 minutes there will be 486 gallons of water drained.