Answer:
Catherine's sister ate 2/15 gallons of the ice cream.
.
Step-by-step explanation:
Let be the amount of ice cream that Catherine's sister ate, in gallons.
- Original amount: 1 gallon.
- What Catherine ate:
gallons.
- What Catherine's sister ate is assumed to be
gallons.
- What's left:
gallons.
Consider the relationship:
.
That is:
.
Add to both sides of this equation:
Substract from both sides:
.
Convert the denominator of all three numbers on the left-hand side to
.
.
In other words, Catherine's sister ate gallons of the ice cream.