Final answer:
Mrs. Lassig spent 7/24 hours, or approximately 0.29 hours, making the desserts for the party.
Step-by-step explanation:
To find how long Mrs. Lassig spent making desserts, we first need to determine the total time it took her to make food for the party. We know that it took her 3 1/2 hours in total. Additionally, we are given that she spent 12 of that time making desserts. To find the time spent making desserts, we can set up a proportion:
3 1/2 hours = 12 desserts
x hours = 1 dessert
By cross-multiplying, we find: (3 1/2) * (1) = 12 * (x)
Converting the mixed number to an improper fraction, we have: (7/2) * (1) = 12 * (x)
Next, we simplify the equation: 7/2 = 12x
Dividing both sides of the equation by 12, we get: (7/2) / 12 = x
Simplifying the left side of the equation, we have: 7/24 = x
Therefore, Mrs. Lassig spent 7/24 hours, or approximately 0.29 hours, making the desserts.