Pre calc matrices! any help appreciated

another one:
x + 4y -2z = 0
2x + y + z = 6
-3x + 3y -5z = -13

<3

Mustafa contributes 11% of his $67,200 annual salary to his 401k plan. what is his pretax income

Apatient is given 50 mg dose of medicine the medicines effectiveness decreases every hour at a constant rate of 40% what is the exponential decay function that models this scenario how much medicine will be left in the patients system after 2 hours

Jamie went to home depot.she bought 25 bags of soil that cost $9 per bag.she bought 15 pots at $8 each, and she bought 23 bags of pebbles at $15 each.she used a coupon that gave her $5 off for every 100 dollars she spent. how much did jamie pay at the end?