1. At an elementary school, it's picture day. Two picture packages are available. Package 1 contains one class picture and ten wallet-size pictures for a cost of $19. Package 2 contains two
class pictures and fifteen wallet-size pictures. The cost of Package 2 is $31. Find the cost of an
individual class picture and the cost of an individual wallet-size picture.

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Step-by-step explanation:

Let c and w represent the per-picture cost of the class picture and a wallet-size picture, respectively. The two packages can be described by ...

  c +10w = 19

  2c +15w = 31

Subtracting the second equation from twice the first, we get ...

  2(c +10w) -(2c +15w) = 2(19) -31

  5w = 7

  w = 1.40

Substituting into the first equation, we can find the cost of a class picture.

  c + 10(1.40) = 19

  c = 5 . . . . . . . . . . . subtract 14

A class picture costs $5; a wallet-size picture costs $1.40.

answer: -8.2562234e+13