Declare textfield variables to work multiple times in a if statement (swift4)

my code below is is in a textfield button. The problem is that the val1 to val3 can only be used in one if statement. How can I declare the bars to be used multiple times within that if statement.

   if  let   val1 = Int(a1.text!), let val2 = Int(a2.text!), let  val3 = Int(b1.text!)
    {
        let sum = val1 + val2
            let sum2 = val1  + val3

    }
    if a2.text == "$"{
        a1.text = String(sum2)
    }