At a concession stand, 9 slices of pizza and 5 soft pretzels cost $33.25. If 6 soft pretzels and 4 slices of pizzas cost $19.50, what is the cost of a soft pretzel and a slice of pizza?

Let x and y represent the costs of a pizza slice and a soft pretzel, respectively. The two purchases can be described by ...
  9x +5y = 33.25
  4x +6y = 19.50

A graph shows the solution of these equations to be
  (x, y) = (3, 1.25)

The cost of a soft pretzel is $1.25.
The cost of a slice of pizza is $3.00.