Developing Data Products Final Project - The Interactive Tip Counter

shinyUI(fluidPage(
  titlePanel("How much should I tip?"),
    sidebarLayout(
    sidebarPanel(
      h3 ("Total bill in USD"),
      h5 ("Slide me! and then Select how good was the Service"),
      sliderInput("slider1","USD",min = 1, max = 250,value = 1, step=0.1), 
      selectInput("select","How was the service?", 
                   choices = list("Okay"=1,"Good"=2, "Excelent"=3),
                   selected = 1),
     actionButton("button","How Much?")
        ),
    mainPanel(
       h3 ("So the total amount going on my tip is!"),
       h4 (textOutput("text1"),style = "color:green"),
       h4 ("Dollars",style="color:green"),
    )
  )
))

Help text omited to appreciate the code (links at the end)

shinyServer<- function(input, output,session) {
   observeEvent (input$button, {
    if(input$select=="1"){
    value <- 0.15    
  } else {
    if(input$select=="2"){
      value <- 0.18   
    } else {
      value <- 0.2
    }
  }
  n <- input$slider1 * value 
  output$text1 <- renderText(n)
}
)
}