Since you are not allowed to draw a black marble, then you have only 7 ways to draw either a blue or a red marble. The sum of all marbles is 10. So the probability of not drawing a black marble is 7/10 and the probability of drawing a red marble is 2/10 or 1/5.
Answer=I
15(x+3)+11x represents the total cost
To solve for this, let's look at the information that we know...
26 students go on the trip
15 students pay $3 more for an additional class (x+3)
26-15=11
11students pay, x, the price of the trip.
So 15(x+3) represents the 15 students who pay for both the trip and the automotive class, and 11x represents the students who simply just pay for the cost of the trip.
Thus, 15(x+3)+11x represents the scenario
The answers is Rational. hope that helps