So, the cab company charges a flat fee of $4 per cab ride, meaning 4 has no variables in the equation. Now, x is the distance, and the cab company charges $2 per mile driven. Per mile driven is a distance unit, so the x goes with the 2. From that, you can get that the cost is equal to 4 dollars plus 2x (2 times the distance in miles). This is y = 2x+4.
An event has probability 1 if you're certain that it will happen. You are sure to pick a marble that's either yellow, green, red, or blue. So, this probability is 1.
There are more yellow marbles than blue marbles, so it's actually more likely that you'll pick a yellow one, rather than the blue one.
The probability of picking a green marble is given by the number of green marbles divided by the total number of marbles. Compute this ratio and see what you get.
Similarly, the probability of picking a black marble is given by the number of black marbles divided by the total number of marbles. There are no black marbles, so...
