A delivery service charges based on the weight and distance of packages. They offer three service levels: Standard, Express, and Overnight. The table below shows the cost per pound for local delivery for each service level.

| Service | Cost per pound ( $) ∣∣ : - - - - - - - - ∣ : - - - - - - - - - - - - - - - - - ∣∣ St an d a r d ∣1.50∣∣ E x p ress ∣2.00∣∣ O v er ni g h t ∣3.50∣ O na p a r t i c u l a r d a y, t h eser v i ce d e l i v ere d a t o t a l o f 800 p o u n d so f p a c ka g es . T h e w e i g h t o f p a c ka g es d e l i v ere d b y t h e O v er ni g h t ser v i ce w a s 150 p o u n d s . I f$ x $re p rese n t s t h e w e i g h t in p o u n d so f p a c ka g es d e l i v ere d b y t h e St an d a r d ser v i ce an d$ y $re p rese n t s t h e w e i g h t in p o u n d so f p a c ka g es d e l i v ere d b y t h e E x p ressser v i ce, w hi c h o f t h e f o ll o w in g e q u a t i o n sre p rese n t s t h ere l a t i o n s hi p b e tw ee n$ x $an d$ y $?$