Im not an expert or anything, but i think for the innequality, i would say
as far as the amount of people she can invite, do 500-100=400 because of the setup fee, then, to find how many people she can invite. 400÷6.50 which leaves you with the highest amount of people she can invite without going over budget, as 61.
as far as the amount of people she can invite, do 500-100=400 because of the setup fee, then, to find how many people she can invite. 400÷6.50 which leaves you with the highest amount of people she can invite without going over budget, as 61.