Given that the augmented matrix in row-reduced form is equivalent to the augmented matrix of a system of linear equations, do the following. (Use x_{1}, x_{2}, x_{3}, and x_{4}, as your variables, each representing the columns in turn.)

1

0

0

0

7

0

1

1

0

−1

0

0

0

1

4

Find the solution or solutions to the system. (If there are infinitely many solutions, express your answer in terms of the parameters t and/or s.)