Ibu membeli kue yang dapat bertahan selama 5/7 minggu. Jika kue tersebut sudah disimpan selama tiga hari 18 jam. Berapa sisa waktu kue dapat bertahan?

1. Break Down the Problem

We need to determine how much longer the cake can last after being stored for 3 days and 18 hours. We start by converting the lifespan of the cake into the same unit (days) and then subtract the time it has already been stored.

2. Relevant Concepts

1. Convert the lifespan from weeks to days.
2. Convert the stored time from days and hours to days.
3. Subtract the stored time from the total lifespan.

3. Analysis and Detail

1. Convert Cake Lifespan from Weeks to Days

   • The lifespan of the cake is $\frac{5}{7}$ weeks.
   • Since 1 week = 7 days: $\text{Lifespan in days} = \frac{5}{7} \times 7 = 5 \text{ days}$

2. Convert Stored Time into Days

   • Stored time is 3 days and 18 hours.
   • First, convert 18 hours into days: $18 \text{ hours} = \frac{18}{24} \text{ days} = 0.75 \text{ days}$
   • Therefore, the total stored time in days is: $3 \text{ days} + 0.75 \text{ days} = 3.75 \text{ days}$

3. Calculate Remaining Time

   • Now we subtract the stored time from the total lifespan: $\text{Remaining time} = \text{Lifespan} - \text{Stored time} = 5 \text{ days} - 3.75 \text{ days} = 1.25 \text{ days}$

4. Verify and Summarize

The remaining time for the cake to last is verified by making sure all time conversions and subtractions were correctly computed.

Final Answer

The cake can last for an additional 1.25 days.