SLOPE, WICH ONE IS PROPORTIONAL WHICH ONE ISNT? Help ASAP

David bought a poster for an art project. the poster is 2.7 feet wide and 3.9 feet tall. what is the area of the poster?

Jamie went to home depot.she bought 25 bags of soil that cost $9 per bag.she bought 15 pots at $8 each,and she bought 23 bags of pebbles at $15 each.she used a coupon that gave her $5 off for every 100 dollars she spent.how much did jame pay at the end?

Witch represents the inverse of the function f(x)=1/4x-12