# Algebra help!

posted by
**Kristen**
.

Please help and I would appreciate an explanation as to how you got to the answer.

1.) Solve the system by triangularizing the augmented matrix and using back substitution.

0.09x-0.15y+0.39

-0.18x+0.35y=-0.88

2.) Solve the system by triangularizing the augmented matrix and using back substitution.

-x-y+z=1

x-y-4z=-7

4x+y+z=6

3.) Perform the indicated row operation, then write the new matrix.

-4 4 | 4

9 -6 | 5 -2R1+ R2 ---> R2