Hey Victoria! So here you first found the rate constant for this reaction by using the half life equation for first order. k= 0.046208812min ^-1. Great! Next what you need to do is assume that we are starting with 100 for the initial concentration, you can also use 1 instead of 100 since they want a fraction here. Then you solve for final concentration after 2 hours. Once you have the final concentration, to find fraction of original reactant you divide final over initial. Hope that helps, let us know if you have any other questions about this!