Final answer:
Christina's mom spent 3.5 hours baking and decorating the cake after spending 8.5 hours on other party preparations, adding up to a total of 12 hours spent preparing for the party.
Step-by-step explanation:
Christina's mom spent a total of 12 hours preparing for the birthday party. To calculate the time she spent baking and decorating the cake, we need to subtract the time spent on the other activities from the total time. Here's a breakdown of her time spent:
- Balloons: 1 hour
- Presents: 3 hours
- Decorating the house: 3.5 hours
- Pinata: 1 hour
The sum of time spent on these activities is:
1 + 3 + 3.5 + 1 = 8.5 hours
Now we subtract the 8.5 hours from the total preparation time of 12 hours:
12 - 8.5 = 3.5 hours
Therefore, Christina's mom spent 3.5 hours baking and decorating the cake.
To find the remaining time, we subtract the sum of these activities from the total time spent preparing, which is 12 hours.
Total time spent on other activities: 1 hour + 3 hours + 3 hours + 1 hour = 8 hours
Remaining time for baking and decorating the cake: 12 hours - 8 hours = 4 hours.
Therefore, Christina's mom spent 4 hours baking and decorating the cake.