### Brain Teasers

# How Many Doctors

A group of doctors attended a conference. All but 40 were cardiologists. All but 50 were pediatricians. All but 60 were surgeons. These were the only types of doctors in attendance. How many in all attended the conference?

### Answer

The total attendance was 75.x = total attendance

x-40 = total cardiologists

x-50 = total pediatricians

x-60 = total surgeons

Final equation:

x = x-40 + x-50 + x-60

x = 3x - 150

-2x = -150

x = 75

35 cardiologists

25 pediatricians

15 surgeons

----

75 total attendees

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