By adding the 1st and third equation together, you get rid of z and end with 7x+8y=13. The second equation will be the second equation and 2 times the first equation, so the will yield 3x+8y=1. Now, you solve this system of equations and get x3, y=-1, and z=-4
24/2=12 so you would do 120/12 and get 10. Your answer is 10 hours.
(Kevin) y= k-6 - k minus six
(Melanie) y= 2(k-6) - two times k minus six
K, only got that far... sorry