A group of students is taking two courses in the summer: biology and math. Based on past experience we know that 75% of students taking the biology course will pass the class (i.e., the probability a student will pass the biology course is .75), we also know that 70% of students taking the math course will pass the class. The probability of passing both courses, biology and math, is .55 (or 55%). Let B = pass biology and M = pass math.