Answer:
A. 4^-2•3 .............................
I believe it is 4/12 since you have a total of 12 marbles and only 4 are red plastic ones
To solve this problem you must apply the proccedure shown below:
1. She has a total of 50 DVDs of 90 minutes each one of them. The cost of each DVD was 11€.
2. Therefore, to calculate the total cost of the collection, you must multiply the cost of each DVD by the total number of them:
€
3. To calculate the total minutes of the collection, you must multiply 90 minutes by the total number of DVDs:

Therefore, the answer is: 550€ and 4500 minutes.
C.
6 is a constant, so we know that y is greater than or equal to 6.
x is just a variable, but it has to be positive, so it could be anything greater than or equal to 0.
Total flour = white flour + wheat flour, therefore y = x + 6.
72% as a decimal is 0.72.
72% as a fraction is 72/100 = 18/25.