Multiply both sides by 2 to get rid of the fraction on the right side:

Divide both sides by h to get b by itself. The following expression will be your answer:
Answer:
50%
Step-by-step explanation:
''What is the probability that she selected the biased coin?”
When we have n possible outcomes of an event and all of them have the same probability of appearance, then in theory each possibility has a probability 1/n of being the result of the event.
In this case the event is choosing randomly a coin out of 2, so no matter what the biased coin is or the results we get when we toss it, the probability of choosing the biased coin is ½ = 0.5 or 50%.
In order to determine the number of students surveyed, we will count the number of students in each sub-group.
Students that did not engage: 279
All three behaviours: 90
113 smoked cigrarettes and used illegal drugs: