Question 177481
Let x be the number of 32 cent stamps and y be the number of 20 cent stamps.  Then {{{x + y = 16}}}.  The value of the 32 cent stamps  is 32x and the value of the 20 cent stamps is 20y, and the total value of the stamps is 392 cents, so:


{{{32x + 20y = 392}}}, but since we also know that {{{x + y = 16}}} and we can then say {{{x = 16 - y}}}, we can substitute for x in the value equation:


{{{32(16 - y) + 20y = 392}}}


Now all you need to do is solve the equation for y giving you the number of 20 cent stamps, and then subtract that value from 16 to get the number of 32 cent stamps.