Rollback Distance Calculation for a Car on a Slope

[camel-man]

Homework Statement

A car traveling at 24.0m/s runs out of gas while traveling up a 20.0degree slope.
How far up the hill will it coast before starting to roll back down?

Homework Equations

Vf^2=Vi^2-2a(g*sin(20)(Xf-X0)

The Attempt at a Solution

I don't know if that is correct formula but I don't know how to solve for Xf

 

[mukundpa]

Yes you may solve using this formula

 

[camel-man]

when i enter in sin(20) my calculator is .34 is that on track? it doesn't seem right