In a exam 80% students passed in accountancy, 85% paased in mathematic ,75% passed in both subject. If 45 students fail in boths subject than what is the total number of students?

Answer 1

the number who passed either or both is

.80+.85-.75 = 0.90

So, 10% of x students failed both:

45 = 0.10x
. . .