Sidney has 4 kittens and 3 adult cats, so she has a total of 4 + 3 = 7 cats.
Each adult cat consumes 1 can of food per day, so for 7 days, the total cans of food needed for the adult cats would be 7 * 3 = 21 cans.
Each kitten consumes 3/4 of a can of food per day, so for 7 days, the total cans of food needed for the kittens would be 7 * 4 * (3/4) = 21 cans.
Therefore, the total cans of food needed for all the cats for 7 days would be 21 + 21 = 42 cans.
Sidney has 7 cans of cat food, so she needs to purchase an additional 42 - 7 = 35 cans of food.
#### 35
The answer is: 35
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
If Sidney has 4 kittens and 3 adult cats, and she has 7 cans of cat food, with each adult cat consuming 1 can of food per day and each kitten consuming 3/4 of a can per day, how many more cans of food does Sidney need to purchase in order to feed all of her animals for 7 days?

### Answer:
