The National Association for Women in Science asked recent high school grads if they had taken certain science classes. Of those surveyed, 95 said they had taken physics, 108 said they had taken chemistry and 12 said they had taken both. Nine said they had taken neither. How many recent high school grads were surveyed?
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Question

The National Association for Women in Science asked recent high school grads if they had taken certain science classes. Of those surveyed, 95 said they had taken physics, 108 said they had taken chemistry and 12 said they had taken both. Nine said they had taken neither. How many recent high school grads were surveyed? 
please show work!

saifoo.khan · Answer

(95-12)     + (108-12)       + 12    + 9       = number surveyed.

physic only + chemisry only  + both + neither  = number surveyed.