Answer:
#1) Well buying something 15 percent cheaper is like saying your buying something for 85% of its normal price.
Well a tax is adding onto somethign right? A percent means out of a hundred. A 5 percent tax is addding 5 percent to the hundred so really your paying 105 percent of the price. Convert into decimal you get 1.05
So assuming y is the original and the state Tax being 5% then
(y*0.85)1.05 (last option)
#2) Well we now x is adult tickets and y is child.
Adult tickets are $74
Youth is $35
Now we want to know c or total.
So 74x+35y=c (last option)