How do I set this up and how do I do the calculations?

The message: 39 57 7 10 11 11 36 44 5 5 33 48 14 19 19 19 was encoded with matrix A.

A =| 1 2 |

.....| 1 3 |

| 1 2 | 39 57 7 10 11 11 36 44

| 1 3 | 5 5 33 14 19 19 19 19

or

| 1 2 | 39 7 11 36 5 33 14 19

| 1 3 | 57 10 11 44 5 48 19 19

(1) / ( (1)(3) - (-1)(-2) )

-1 * | 3 -1 |

.......| -2 1 |

| -3 1 |

| 2 -1 |

and then I'm suppose to multiply this by the message. But how is this done?

-3(39) = -117 ?