Let

x = # of chocolate chip muffins

y = # of oatmeal muffins

z = # of cranberry muffins

The 1st sentence & the last question gives you the first equation:

.15x + .20y + .25z = 2.50

The 2nd sentence gives you the second equation:

z = 2x or 2x - z = 0

The 2nd sentence and last question gives you the final equation:

x + y + z = 12

So your system of equations would be

.15x + .20y + .25z = 2.50

2x - z = 0

x + y + z = 12

Now solve. (Look at your previous threads on systems of linear equations for hints.) The value of y will give us the answer to the problem.

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