66 is 15% of what amount....
66 = 0.15x
66/0.15 = x
440 = x......so $ 66 is 15% of $ 440
Solution: Yes, the random variable y will have a binomial distribution. Because there are two possible outcomes 1. number of days of rain and 2. number of days of no rain.
The parameters of binomial distribution are
and 
The parameter n is given as the number of day's under consideration.

The parameter p is not given, but it can be estimated by number of days it rained divided by the total number of days under consideration.

7(-3) is an example of multiplication. What the question wants you to do is multiply the outside number (7) by the inside number (-3).
Basically you are just multiplying -3 x 7.
Your product is -21
The amount of money you still owe to the credit card company is called a credit card balance.