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equations:

Fn=mg

Fk=μkFn

x-xo=vot-(1/2)at^2

attempt at solution:

Fn=mgcos12

=(9.8)(cos12)(m)

=9.59m

fk=μkFn

fk-mgsin12=ma

μkgcos12-gsin12=a

(.560)(9.8)(cos12)-(9.8)(sin12)=a

a=3.33

x-xo=vot-(1/2)at^2

23=20t-(1/2)(3.33)t^2

0=-1.665t^2+20t-23

quadratic formula gave -1.288, -10.72

v=vo+at

v=20+(-3.33)(1.05)

v=16.5035

obviously can't have -t so I just plugged in +1.05 into that last equation, but I'm just trying to figure out what I did wrong because this was the wrong answer. Thank you!