How much does it cost for two specials and 2 milks if 4 specials and 2 glasses of milk cost 28.00 or 3 specials and 4 glasses of milk cost 26.25?

Answer 1

Because this a linear algebra question, the first thing that we do is set up our augmented matrix:

[3 4| 26.25]

[4 2| 28]

The first column is the "specials" and the second column is "glasses of milk".

Next, we want to get the matrix into row reduced echelon form:

~add -1 * row 2 to row 1

[-1 2 | -1 3/4]

[4 2 | 28]

~add 4 * row 1 to row 2

[-1 2 | -1 3/4]

[0 10 | 21]

~divide row 2 by 10

~divide row 1 by -1

[1 -2 | 1.75]

[0 1 | 2.1]

~add 2 * row 2 to row 1

[1 0 | 5.95]

[0 1 | 2.1]

Thus we see that a special costs 5.95 and a glass of milk costs 2.1

Thus an order of 2 milks and 2 specials will cost

11.90 + 4.2 = 16.10