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? Let's answer step by step:
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: 135.