Q: Nick's cell phone was initially empty but was then charged for 45 minutes and has reached a 25% charge. How much longer must the cell phone be charged to reach 100% charge?
A: The ratio between the time charged and the time to be charged is 100 / 25 = 4. To reach 100%, the cell must be charged for 45 minutes * 4 = 180 minutes. Subtracting the 45 minutes that Jimmy already used to charge the cell phone, there are still 180 - 45 = 135 minutes of charging time left. The answer is 135.

Q: Ellie has 8 pairs of shoes. Riley has 3 fewer. How many pairs of shoes do they have in all?
A: Riley has 3 fewer pairs of shoes than Ellie's 8, so 8 3 = 5 pairs of shoes. Together, they have Ellie's 8 + Riley's 5 = 13 pairs of shoes. The answer is 13.

Q: John decided to start rowing around a square lake. Each side of the lake is 15 miles. Jake can row at twice the speed he can swim. It takes him 20 minutes to swim 1 mile. How long, in hours, does it take to row the lake?
A:
The perimeter of the lake is 4 * 15 = 60 miles. He swims at a speed of 60 / 20 = 3 mph. So he rows at a speed of 3 * 2 = 6 mph. That means it takes him 60 / 6 = 10 hours to row around the lake. The answer is 10.