Finish lesson on multiple arguments and default values

Signed-off-by: Michael Tang <michael.h.tang@gmail.com>

arguments.js

@@ -0,0 +1,29 @@
+// Multiple arguments
+let add = function (a, b, c) {
+    return a + b + c
+}
+
+let result = add(10, 1, 5)
+console.log(result)
+
+// Default arguments
+let getScoreText = function (name = 'Anonymous', score = 0) {
+    return 'Name: ' + name + ' - Score: ' + score
+}
+
+let scoreText = getScoreText(undefined, 99)
+console.log(scoreText)
+
+// Challenge area
+// total,tipPercent = 0.2
+
+let calculateTip = function (total, tipPercent = 0.2) {
+    let tip = total * tipPercent
+    return tipPercent * 100 + '% Tip on $' + total + ' is $' + tip
+}
+
+let tip = calculateTip(100)
+console.log(tip)
+
+let tip2 = calculateTip(100, 0.15)
+console.log(tip2)